1981

c. 2

NBS BUILDING SCIENCE SERIES 135

Energy Measurement in the

Standard Penetration Test

U.S. DEPARTMENT OF COMMERCE • NATIONAL BUREAU OF STANDARDS
NATIONAL BUREAU OF STANDARDS

The National Bureau of Standards' was established by an act of Congress on March 3, 1901. The Bureau's overall goal is to strengthen and advance the Nation's science and technology

and facilitate their effective application for public benefit. To this end, the Bureau conducts

research and provides: (1) a basis for the Nation's physical measurement system, (2) scientific and technological services for industry and government, (3) a technical basis for equity in trade, and (4) technical services to promote public safety. The Bureau's technical work is per- formed by the National Measurement Laboratory, the National Engineering Laboratory, and

the Institute for Computer Sciences and Technology.

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physical and chemical and materials measurement; coordinates the system with measurement

systems of other nations and furnishes essential services leading to accurate and uniform

physical and chemical measurement throughout the Nation's scientific community, industry,

and commerce; conducts materials research leading to improved methods of measurement,

standards, and data on the properties of materials needed by industry, commerce, educational

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Absolute Physical Quantities^ — Radiation Research — Thermodynamics and

Molecular Science — Analytical Chemistry — Materials Science. THE NATIONAL ENGINEERING LABORATORY provides technology and technical ser- vices to the public and private sectors to address national needs and to solve national problems; conducts research in engineering and applied science in support of these efforts; builds and maintains competence in the necessary disciplines required to carry out this research and technical service; develops engineering data and measurement capabilities;

provides engineering measurement traceability services; develops test methods and proposes

engineering standards and code changes; develops and proposes new engineering practices;

and develops and improves mechanisms to transfer results of its research to the ultimate user. The Laboratory consists of the following centers:

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research and provides scientific and technical services to aid Federal agencies in the selection,

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economy in Government operations in accordance with Public Law 89-306 (40 U.S.C. 759), relevant Executive Orders, and other directives; carries out this mission by managing the Federal Information Processing Standards Program, developing Federal ADP standards

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'Headquarters and Laboratories at Gaithersburg, MD, unless otherwise noted; mailing address Washington, DC 20234. 'Some divisions within the center are located at Boulder, CO 80303.
Acker M-2

r- 1 —T

1 1

I -1 1

CME45 D V 0 OO A o

CME45B 0

CME 55 o

O O V

Drown(iSN)U| rnv. comm.

0 DO VO

CME 65

\J ^rhmprtmann £ <^mith (1Q77I ^ obiiiiici iiiidiiii M oiiiiin |i9(/j

CME 550 Schmertmann (19801 Priv. Comm.

CME 750

SteinbefE (1980) Priv. Comm.

Joy B-12 This study

Meyhew 1000 o

Failing 1500 o o

Mobile B-33 o Data includes donut and safety

Mobile B-34 a o

hammers plus the safe-T-driver.

Data corrected to represent maximum

Mobile B-61

theoretical energy, i.e. for a 40 ft |13mj drill rod length.

Mobile B-80

1 1 1 1 1 1 1 1

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 aS

ENERGY RATIO FOR F(t), ERj =Ej/E*

Fig. 3.16 Summary of data to date of energy ratio for F(t), ER^

,

for thirteen drilling rig models, (replaces figure on page 54.)
Errata to accompany

National Bureau of Standards Building Science Series 135

Energy Measurement in the Standard Penetration Test

1. The photograph on page 11 was inadvertently cropped on the left side.

A scale drawing of a pin guided hammer is shown below. (See also

page 197 of the January issue of the ASCE Journal of the Soil Mechanics

and Foundations Division.)

1. The photograph on page 27 should be rotated 90° clockwise for proper

viewing

3. The data from Steinberg (1980) as represented by a square symbol on Figure 3-16 is incorrect as the drill stem lergth correction factor,

using Figure 3-12 was applied twice. A corrected figure is on the reverse side. The data in Table 3-A for Steinberg (1980) reflects

the corrected value of ER •

(see over)
NBS BUILDING SCIENCE SERIES 135

Energy Measurement in the

Standard Penetration Test

William D. Kovacs

Lawrence A. Salomone

Felix Y. Yokel

Center for Building Technology

National Engineering Laboratory

National Bureau of Standards

Washington, DC 20234

U.S. DEPARTMENT OF COMMERCE, Malcolm Baldrige, Secretary

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director

Issued August 1981

Library of Congress Catalog Card Number: 81-600101

National Bureau of Standards Building Science Series 135

Nat. Bur. Stand. (U.S.), Bldg. Sci. Ser. 135, 99 pages (Aug. 1981)

CODEN: BSSNBV

For sale by the Superintendent of Documents. U.S. Government Printing Office Wasliington, D.C. 20402 - Price $4.50

ABSTRACT

Geotechnical engineers in the United States commonly use the Standard

Penetration Test, SPT, in subsurface investigations for routine foundation

designs. It has been said that perhaps up to 80 to 90 percent of the routine

foundation designs are accomplished by the use of the SPT "N" value. Despite

efforts to standardize more details of the SPT procedure, variability between

tests is inherent under present guidelines.

A field measurement system and procedure which measures the energy delivered

by a drill rig system were developed and successfully used to study the factors

which affect delivered energy. Results are presented which indicate the energy

delivered by certain drill rig systems used in engineering practice. Also, the

transmission characteristics of certain hammer/anvil systems are examined.

Guidance on the need to measure the actual fall height of the hammer during the

Standard Penetration Test is provided based on the findings of the study.

Key words: energy measurement; field instrument force measurement;, field

testing; in-situ testing; soil mechanics; transducers.

iii
TABLE OF CONTENTS

Page

ABSTRACT iii

LIST OF FIGURES v LIST OF TABLES viil

NOTATION Ix

1. INTRODUCTION 1 1.1 General 1 1.2 Historical Background of the Standard Penetration Test 2 1.3 Limitations of the Standard Penetration Test 5

1.4 The Role of the Standard Penetration Test in Engineering

Practice 7 1.5 Purpose of This Study 7

2. FIELD TESTING 11

2.1 Test Instrumentation and Procedures 11

2.2 Test Procedure 17

2.3 Methods of Data Reduction and Computations 19

3. PRESENTATION AND DISCUSSION OF TEST RESULTS 27

4. SUMMARY AND CONCLUSIONS 63

5. ACKNOWLEDGMENTS 67

6. REFERENCES 69

7. APPENDIX A - TABULATION OF DATA A-1

COVER: Performing the Standard Penetration Test using the cathead and rope

method. A donut type hammer is being used.

iv
LIST OF FIGURES

Page

Figure 1-1 Sketch showing typical SPT cathead and rope setup 3

Figure 2-1 Sketch of instrumentation set up to measure fall height,

velocity just before impact, and force in the drill stem .... 12

Figure 2-2 Instrumentation schematic diagram lA

Figure 2-3 Photograph of test setup showing targeted safety hammer,

instrumented section of drill stem, load cell, and top and

bottom scanner, opposite target. Angle frame is adjusted

to be parallel to hammer prior to test 15

Figure 2-4 Typical output data from top and bottom scanner 16

Figure 2-5 Example of how fall height is evaluated using a targeted

hammer and light beam scanners 18

Figure 2-6 Sequence of events in data reduction and computations of

the velocity just before impact and energy values at impact

in the drill stem. Data from blow number 87, series 8 20

Figure 2-7 Correction factor to account for the non-ideal position

of the load cell and the length of drill rods. (After

Schmertmann, 1980) 23

Figure 3-1 Hammer velocity just before impact versus fall height for

Series 1 data 31

Figure 3-2 Hammer velocity just before impact versus fall height for

Series 2, 3, and 4 data (least square fit of data in

table A-1) 32

Figure 3-3 Energy ratio for velocity versus fall height for Series 2,

3, and 4 data 34

Figure 3-4 Energy ratio for velocity versus energy ratio for F(t) for

Series 2, 3, and 4, corrected for drill stem length using

figure 2-7 35

Figure 3-5 Energy ratio for velocity versus number of turns for a Mobile

Drilling Company, B-50 rig (after Kovacs et al., 1975) 37

Figure 3-6 Energy ratio for velocity versus number of turns for Series 1

through 18 38

v
LIST OF FIGURES (CONTINUED)

Page

Figure 3-7 Energy ratio for F(t) versus number of turns for Series 1

through 18 41

Figure 3-8 Energy ratio for velocity versus energy ratio for F(t) for

Series 1 through 18 and Series 28 through 31 42

Figure 3-9 Energy ratio for velocity versus number of turns for

Series 19 through 27. Number beside points indicate number

of data points <> . 44

Figure 3-10 Energy ratio for F(t) versus number of turns for Series 19

through 27 45

Figure 3-11 Energy ratio for velocity versus energy ratio for F(t) for

Series 19 through 27 46

Figure 3-12 Theoretical relationship between efficiency of the hammer

system Ej^/E*, versus length of drill stem for AW rod (After

Schmertmann, 1980). Relationship is for the case when the

load cell is at the ideal position at the point of impact ... 47

Figure 3-13 Energy ratio versus number of turns for Series 28 through

31 48

Figure 3-14 Data for Series 32 through 35. a) ER for velocity versus number of turns, b) ER for F(t) versus number of turns, and

c) ER for velocity versus ER for F(t) 50

Figure 3-15 Energy transfer ratio ERj-ZERy versus the measured time

for the return wave, 2 ii/c 51

Figure 3-16 Summary of data to date of energy ratio for F(t), ER-j^, for

13 drilling rig models 54

Figure 3-17 Energy ratio for F(t), ERj_, versus drill stem length for the

CME 45 drilling rig 56

Figure 3-18 Energy ratio for F(t), ERj^, versus drill stem length for the

CME 55 drilling rig 57

Figure 3-19 Drill rig operator's performance as measured by the (a) fall

height and (b) fall height standard deviation versus number

of turns data 58

vi
LIST OF FIGURES (CONTINUED)

Page

Figure 3-20 Variation of fall height during the performance of the SPT

by four experienced drill rig operators under their usual

test setup 59

Figure 3-21 Variation of fall height during the performance of the SPT

(after Kovacs et al. , 1975) 60

vii
LIST OF TABLES

Page

Table 1-1 Factors Affecting the Results of the SPT 6

Table 1-2 The Use of the Standard Penetration Test 8

Table 2-1 Summary of Energy Ratio Definitions 26

Table 3-1 Summary of Drill Rigs Tested and Test Results 29

Table 3-2 Detailed Measured Data and Energy Ratios for Series 1 30

Table 3-3 Summary of Average Energy Ratios from Tables 3-2 and A-1

through A-17 39

Table 3-4 Tabulation of Energy Ratios to Date for Operator's Usual

Testing Conditions 33

Table A-1 Results for Series 2, 3, and 4 75

Table A-2 Results for Series 5, 6, and 7 76

Table A-3 Results for Series 8 77

Table A-4 Results for Series 9 78

Table A-5 Results for Series 10, 11, 12, and 13 79

Table A-6 Results for Series 14 80

Table A-7 Results for Series 17 81

Table A-8 Results for Series 19 82

Table A-9 Results for Series 20, and 21 83

Table A-10 Results for Series 22, 23, and 24 84

Table A-11 Results for Series 25, 26, and 27 ' 85

Table A-12 Results for Series 28, 29, 30, and 31 86

Table A-13 Results for Series 32 87

Table A-14 Results for Series 33, 34, and 35 88

viii
NOTATION

A = cross sectional area of the drill rods, cm^

c = compressive or p wave velocity of sound in the steel drill rod, m/s

Dj. = relative density

E = Young's modulus of the drill rods, N/m^

E* = theoretical free fall energy assuming a 762 mm (30 in) fall, equals

475 J (4200 in-lbs)

E-j^ = ENTHRU, the energy reaching the sampler, the energy for F(t), i.e. the

incident energy in the drill rods as determined from Eq. 5; equals Ej-, J

Ey = energy for velocity, i.e. kinetic energy just before impact, J

Ej. = energy for F(t), i.e. the energy in the drill rods from the first

compression wave pulse, J

ERj^-j^ = energy ratio just prior to impact based on a back calculation of stress

in the rod and solving for the required velocity, then computing energy

by 1/2 m

ERj. = energy ratio for F(t) in drill rod based on measured fall height, Ej./WH

ERy = energy ratio for velocity, E^/WH, based on measured fall height

F(t) = force-time history in the load cell during impact

H = measured hamm-'.r fall height, cm

K = a correction factor (figure 3-2)

a = the distance from the point of impact to the bottom of the sampler, m

M = mass of the falling hammer, kg

N = blow count, "N" value, or penetration resistance

p = mass density of the drill rods, kg/m-^

V = velocity of hammer, cm/s

Wj^ = velocity of hammer just before impact, cm/s

ix
NOTATION (CONTINUED)

W = hammer weight, "N"

^ = angle of shearing resistance, degrees

Facing page: Advancing a hove hole w£th

a 15 cm (6 inl diameter hollow stem auger.

Targeted safety hammev just to the left

of the cathead with roipe.

X
1 . INTRODUCTION

1.1 GENERAL

Geotechnical engineers in the United States commonly use the Standard

Penetration Test (SPT) in subsurface investigations for routine foundation

designs. In addition, it has been used to evaluate the "liquefaction potential" of sandy soils. The American Society for Testing and Materials (ASTM)

has a Standard Method for performing the SPT entitled, "Penetration Test and

Split-Barrel Sampling of Soils," D 1586-67 (reapproved 1974). The Standard

1
Penetration Test consists of driving a 5.08 cm (2 in) outside diameter sampling

"spoon" or sampler, with an inside diameter of 3.49 cm (1-3/8 in), a distance of

30.48 cm (12 in) after first "seating" the, sampler 15 cm (6 in) by dropping a 63.5 kg (140 lb) mass from a height of 762 mm (30 in). It should be noted that

the 3.49 cm (1 3/8 in) inside diameter spoon referred to in the ASTM method

assumes the use of a liner. In practice this liner is seldom used. Therefore

the inside diameter of the sampler over the length of the barrel is 3.81 cm

(1 1/2 in). Figure 1-1 provides a sketch of the SPT set up using a "cathead"

and rope along with a cylindrical or donut hammer. To raise the "hammer", the

operator pulls the rope in towards himself until the prescribed fall height is

achieved; to drop the weight, the operator releases the rope around the revolving cathead by "pushing" the rope into the cathead. The operator has the

responsibility to insure a 762 mm (30 in) fall. A mark on the slip or guide

pipe may be used to insure the required fall height but frequently the judgment

of the operator dictates the actual fall height. Typically, an operator accomplishes about 40 blows per minute with this setup . There are several types of

hammers presently in use.

The operator counts the number of blows it takes to advance the sampler each of

three 15 cm (6 in) increments. When the sampler has penetrated 45 cm (18 in)

into undisturbed soil at the bottom of a borehole, the operator adds the number of blows for the second and third increments. This combined number is

called the "blow count" and is customarily designated as "N" or the "N" value. It

is also called the penetration resistance. The "N" value is usually obtained at

intervals determined by the engineer according to his/her experience and regional

practice. Usually SPT borings do not go deeper than 60 m (200 ft).

The test can be used as the primary soil descriptor in a geotechnical

engineering analysis and design or used in conjunction with other laboratory

and field testing procedures. The Standard Penetration Test has served as an indicator of changes in the soil profile and has been correlated with the

soil's capability to resist both shear failure and excessive settlement. To

gain insight into the importance of this field test, a brief historical summary

follows

1.2 HISTORICAL BACKGROUND OF THE STANDARD PENETRATION TEST

The standard penetration test came into being as a result of the development of

dry sample recovery techniques. In the past, subsurface investigations were performed primarily through the use of wash borings. A wash boring involves

the circulation of a water and/or drilling mud mixture to remove the cuttings

from the boring as the hole is advanced. In 1902, Charles R. Gow introduced

the first method of dry sample recovery [Sanglerat, 1972]. He used a 50 kg

(110 pound) weight to drive a 2.54 cm (1 in) outside diameter sampling pipe.

After this method was used for a short time, it became apparent that the

resistance to driving the sampler was influenced by the condition and properties (e.g., strength and density) of the soil. Thus, the term, "penetration

resistance," was then used to define the number of blows required to drive the

sampler a given distance.

2
Note: CROWN SHEAVE(S) AND CATHEAD

CAN BE EITHER DRILL RIG OR

TRIPOD MOUNTED.

Figure 1-1. Sketch showing typical SPT cathead and rope setup.
In 1927, the Sprague and Kenwood Company of Scranton, Pennsylvania, and the Gow

Company, now a subsidiary of the Raymond Concrete Pile Company, introduced the

5.08 cm (2 in) outside diameter split spoon sampler [Fletcher, 1965]. Relatively soon after the introduction of this type of sampler, Harry A. Mohr and

Gordon F. A. Fletcher standardized some details of the test procedure. The

details standardized included: (1) driving the split spoon sampler by dropping

a 63.5 kg (140 lb) mass a distance of 76.2 cm (30 in); and (2) the standard penetration resistance or "N" value was defined as the number of blows required to

drive the 5.08 cm (2 in) outside diameter sampler a distance of 30.48 cm

(12 in). In the mid-1950 's further standardization of the standard penetration

test was introduced by defining the "N" value as the number of blows required

to produce the last 12 (30.48 cm) of 18 (45.72 cm) inches of penetration

[Fletcher, 1965].

When the Standard Method for Penetration Test and Split-Barrel Sampling of

Soils, ASTM D 1586-58 was first approved, further standardization of the SPT was formalized by the American Society for Testing and Materials, [ASTM, 1967].

In this standard, it was specified that the drill rod have a stiffness equal to or greater than a steel rod with a diameter of 4.13 cm (1-5/8 in) or an "A"

sized hollow-drill rod. A stiffer rod is recommended for holes deeper than

15.25 m (50 ft). Also it states in the standard that free fall should be

incurred by the drive weight assembly or driver. Some of the other procedural

details included in the standard are: proper fluid head must be maintained in

the hole when drilling below the water table and the drill bit should be withdrawn slowly to eliminate any loosening of the soil due to upward seepage

forces. A bottom discharge bit should not be permitted when drilling wash

borings. If casing is used, it must not be driven below the sampling elevation. Although this standardization by ASTM appears quite detailed much is

left open to interpretation [Evans, 1974].

Finally, to reduce further the variability due to procedures and equipment in

the standard penetration test, additional recommendations by the International

Commission of the International Society of Soil Mechanics and Foundation Engineering were made [Arce et al. , 1971]. These recommendations were:

(1) The SPT should be performed in each identifiable soil layer or every .92 m (3 ft).

(2) Drilling mud may be used.

(3) The penetration should be measured and the penetration resistance

should be recorded as zero if the spoon advances under its own

weight.

(4) The spoon should not be subjected to more than 50 blows. The

penetration resistance should be expressed as a ratio of the

number of blows to the distance penetrated in inches if 50

blows are required.

Variability between tests is inherent under present guidelines despite the

efforts to standardize more details of the SPT procedure. In the next section

the sources of variability and error are discussed.

4
1.3 LIMITATIONS OF THE STANDARD PENETRATION TEST

In any field or laboratory testing procedure, the ability to reproduce results

is important. In the case of the SPT, the ability to reproduce consistent blow

counts depends on maintaining consistent delivered energy in drilling systems.

Different delivered energies may result in significantly different blow counts

in the same deposit at the same overburden pressure because the SPT blow count

is inversely proportional to the delivered energy [ Schmertmann, 1975].

Casagrande and Casagrande [1968] noticed considerable differences in penetration resistance "N" values obtained by two different boring contractors in sands

at the same depth on the same site in Michigan adjacent to Lake Michigan.

Consequently, a necessary prerequisite for the continued use of the Standard

Penetration Test is an improvement of its reliability, i.e., its ability to

reproduce blow counts. On the other hand, Serota and Lowther [1973] and

Marcuson and Bieganousky [1977] have pointed out from the consistency of their

SPT test results that the Standard Penetration Test blow count is indeed reproducible. An understanding of the factors which affect the penetration resist- ance values and procedures which reduce the wide variation in delivered energy

of drill rigs is therefore necessary.

Factors affecting the reproducibility of the Standard Penetration Test

include: personnel, equipment and procedure. While many of the factors that

affect the test are standardized, many are not. The variability in results

which is caused by not following the standard procedures have been discussed

by Fletcher, [1965] and Ireland et al., [1970]. A summary of the factors

affecting the results of the SPT is presented in table 1-1. More recently

Kovacs et al., [1977] and Kovacs [1979] have demonstrated the wide variability

in the conditions utilized in this supposedly standardized test procedure. In

addition, based on other studies of the Standard Penetration Test, it was con- cluded that the blow count results may be significantly influenced by other

factors. These factors have been summarized by Palacios, [1977] and

Schmertmann, [1975, 1976 and 1979]: (1) the use of drilling mud versus casing

for supporting the walls of the drill hole; (2) the use of a hollow-stem auger

versus casing and water; (3) the size of the drill hole; (4) the number of

turns of the rope around the drum; (5) the use of a small or large anvil;

(6) the length of the depth r.ange over which the penetration resistance is

measured.

Schmertmann [1979] also found that removing the liners from an SPT sampler

designed for liners improved sample recovery and removal but it produced a significant reduction in "N" and tended to make the SPT more dependent on the

sampler end bearing resistance. The percent reduction in "N" increased with

decreasing "N" in any type soil.

The method of ensuring free fall is a large source of variability. Variations

in the effective stress conditions before and during sampling may have equal

importance. A large difference in delivered energies results when the SPT is run using a manila rope and cathead or a "trip monkey." (A trip monkey is the common engineering term for a mechanical trigger released SPT hammer; several

5
Table 1-1. Factors Affecting the Results of the SPT

After Fletcher, 1965, Marcuson et al. 1977, and Schmertmann, 1977

Test Detail Effect on N-value I Estimated Percent

by Which Cause Can Change N

Inadequate cleaning of disturbed

materials in the borehole Decreases |

Failure to maintain sufficient

hydrostatic head in the borehole Decreases | 100%

Variations from the exact 762 mm

(30 in) drop

Either | + 10%

Length of drill rods

< 3 m (10 ft)

10 to 16 m (30 to 80 ft)

> 30 m (100 ft)

Increases | 50%

010%

Any interference with free fall

(using 2 to 3 turns) Increases |

1

to 100%

Using deformed sample spoon Increases |

Excessive driving of sample spoon before the blow count Decreases I

Failure of driller to completely release

the tension of the rope Increases |

Driving sample spoon above the bottom of the casing

Increases I

Use of wire line rather than manila rope Increases |

Carelessness in recording blow count Either |

Insufficient lubrication of the sheave Increases |

Larger size of borehole Decreases | 50%

rt;llcL£a.L-HJll XllLcLVclX ^0 to 12 in instead N5 ^o 18 in

N12 to 24 in versus N5 ^o 18 in

Use of drilling mud versus casing in water

Decreases I

Decreases I

Increases I

15% sands

30% insensitive clays

15% sands

30% insensitive clays

100%

Large vs small anvil Increases I 50%

Use of A rods versus NW rods Either | ± 10%

Larger ID for liners, but no liners Decreases | 10^ sands

30% insensitive clays

6
varieties of this 100 percent free fall device are commercially available.)

Use of a trigger release mechanism better approximates true free fall. Evidence of the wide variation in the measured delivered energies using different

drill rigs is presented by Schmertmann and Smith [1977], Kovacs et al. , [1975],

Kovacs [1979] and in the work reported herein. The significance of this wide

variation in the measured delivered energies becomes clear after considering

the results of a theoretical, experimental and computer study of the force and

energy dynamics of the SPT sampler penetration performed by Schmertmann and

Palaclos, [1979]. They concluded:

(1) "N" varies inversely with ENTHRU(the energy reaching the sampler,

Ej^) to at least N = 50. Most of ENTHRU goes into pushing the

sampler into the soil and

(2) ENTHRU can vary from 30 percent to 85 percent of the free-fall

hammer energy. This Implies that "N" could vary by a factor of

almost three in the same soil due to only one variable, ENTHRU.

From the previous discussion, it can be concluded that numerous mechanical and

human factors as well as the in-sltu conditions of the soil influence the penetration resistance. Soil type, moisture content, density, shear strength,

in-sltu stress conditions and soil sensitivity are some of the soil conditions

which influence the SPT. Consequently it is essential for using the many SPT

correlations found in the literature that the factors affecting the SPT results

be understood. Also, the procedures should be further standardized so that the

effect of these variables can be minimized.

1.4 THE ROLE OF THE STANDARD PENETRATION TEST IN ENGINEERING PRACTICE

Geotechnlcal engineers in the United States commonly use the Standard

Penetration Test in subsurface investigations for routine foundation design.

We estimate that perhaps up to 80 to 90 percent of the routine foundations

design is accomplished by the use of the SPT "N" value. Almost all site

investigations in some areas of the United States Involve the use of the SPT.

The SPT has served as an indicator of changes in the soil profile and has been

correlated with the soil's ability to resist shear failure and excessive

settlement. In addition, it has been used to evaluate the "liquefaction

potential" of sands. Table 1-2 presents a summary of the uses of the Standard

Penetration Test in engineering practice.

1.5 PURPOSE OF THIS STUDY

The Standard Penetration Test is used by the engineering profession to evaluate

the static and dynamic properties of soils and foundations. However, despite

the efforts to standardize more and more details of the test procedures, variability between tests is inherent in present procedures. The purpose of the

work presented in this report was:

7
Table 1-2. The Use of the Standard Penetration Test*

USt I AUTHOR [REFERENChJ

I

Soil Properties (Static)

estimate relative density, Dj., using qualitative relationship I Terzaghi & Peck [1948J, Burmister [1948], between penetration resistance and the relative density. I [Holtz, 1973]

I J

estimate Dj. using quantitative relationship between penetration I Gibbs & Holtz [ 1957], Marcuson & Bieganousky

resistance, effective overburden pressure and relative density, | [1977a, b], Bieganousky & Marcuson [1976, 1977]

I ^

estimate 9 using relationship between penetration resistance, I Peck, et al., [1953, 1974], Meyerhof [1956] relative density and the angle of internal friction, 9 I

I J

estimated undrained shear strength of insensitive and saturated I Terzaghi i Peck [1948], Sowers [1954], Rendon

clays using relationship between penetration resistance and I [1969] undrained shear strength I

Analyses (Static)

shallow foundation design, estimate bearing capacity of sands I Bowles, 1968, 1974 using penetration resistance I

I ^

estimate settlement in sands using penetration resistance I Terzaghi 6. Peck [1948], Meyerhof [1965],

I Peck et al. [1953], D'Appolonia et al. [1968]

I ^

estimate settlement in sand using coefficient of compressibility, I Schultz & Melzer [1965]

Eg and penetration resistance I I

estimate settlement in sands using vertical strain distribution I Schmertmann [1970]

Deep Foundations

estimate static bearing capacity of a single pile using | Meyerhof [1957], Bazaraa [1967], Hordland penetration resistance I [1963]

Soil Properties (Dynamic)

estimate relative density of a sand using penetration resistance I Gibbs & Holtz [1957]

I ^

estimate dynamic shear modulus, G, using penetration resistance I Valera & Donovan [1977]

I ^

estimate shear wave velocity using penetration resistance I Kanai et al. [1956], Ohta et al. [1972],

I Marcuson et al. [1978]

I ^

estimate the liquefaction potential of sands using penetration I Seed [1976, 1979], Seed & Idriss [1971], resistance I Townsend et al. [1978]

* This table partly is based on information provided by Evans [1974] and should not be considered comprehensive,

more comprehensive treatment has been presented by de Mello [1971].

8
(1) Develop a field measurement system to measure the energy

delivered by the drill rig system during the Standard

Penetration Test.

(2) Determine the energy delivered by drill rig systems used in

engineering practice.

(3) Examine the transmission characteristics of certain hammer/anvil

systems used to advance the SPT sampler.

(4) Examine the need to measure the actual fall height of the hammer

during the Standard Penetration Test.

9
Facing page: Dvill vi.g set up over a rotary wash boring. Rope attached to a pin guided hammer. Donut hammer in

center foreground.

10
2. FIELD TESTING

2.1 TEST INSTRUMENTATION AND PROCEDURES

Figure 2-1 shows a sketch of the instrumentation setup used in this study.

The instrumentation consisted of two light beam sensors installed above the

anvil to measure fall height and hammer velocity and a force link and a load

cell installed in the drill stem to measure the stress wave generated in the

drill stem from the hammer blow.

11
TWO LIGHT BEAM

SENSORS AT FIXED SPACING 762mm

130 in) APART

INSTRUMENTATION

CART

(See next figure]

CROWN SHEAVElSj OR PULLEY(S1

TYPICALLY 25mm (lin)

DIAMETER MANILA ROPE

SPT

ROTATING

CATHEAD

Figure 2-1. Sketch of instrumentation set up to measure fall height,

velocity just before impact, and force in the drill stem.

12
The force link is a strain gage instrumented section of drill rod used to

obtain a duplicate force measurement for comparison with the load cell. It

should be noted that after the data was taken, it was realized that the internal threads of the force link were too close to the external position of the

strain gages to render accurate measurements; hence forth, the force link will

no longer be discussed in this report.

The load cell has a capacity of 178 kN (40,000 lb). Figure 2-2 shows a schematic diagram of the instrumentation package used during this study.

The 63.5 kg (140 lb) hammer is surrounded by a target with parallel light

(white) and dark (black) strips. The target was originally made with one-half

in (12.7 mm) thick white and black lines and was photographically reduced to

3.1 mm (1/8 in) lines. The target is shown placed on a safety hammer in the

photograph, in figure 2-3. The target is sensed by two photovoltaic reflective scanners placed exactly 762 mm (30 in) apart on a frame composed of 5 cm X 5 cm (2 in X 2 in) steel angles. The reflective sheeting and the scanner

are used to determine the velocity of the hammer during the hammer fall. As

the target passes the scanner, the reflected light which varies with intensity with each change from black to white is intercepted by the scanner and

converted to electronic signals which are transmitted to the tape recorder.

From the known distance between any two light strips, the time elapsed between

the peaks of the recorded signal, the velocity of the falling hammer can be

calculated.

With appropriate placement of the scanners, it is possible to get a picture of

how the hammer or drive weight travels up and down during each stroke. Typical output data from an oscillograph are shown in figure 2-4. The top trace

corresponds to the top scanner and the bottom trace corresponds to the bottom

scanner. At Location A in figure 2-4, it can be seen that the top scanner is

picking up the top portion of the target as the target is raised. At Location B in figure 2-4, it can be seen that the hammer has stopped moving upward

by the increased spacing of the signal and is starting the downward stroke.

When the hammer gains velocity, the distance between the peaks of the scanners'

output decreases as a point on the target goes from Location B to Location C. At a location to the right of point D, the distance between points for the

lower scanner changes abruptly. At this particular instant, the hammer has

Impacted and is rebounding and is no longer a part of the test. The free-fall

height is then determined by counting the number of peaks from Location A to

Location B, as well as a check on the number from Location B to Location C.

They should be the same. For the specific example shown in figure 2-4, the

amount of the fall height was 79.38 cm (31.25 in) before impact (just before

Location D). The instantaneous velocity is calculated from the elapsed time

between two points one cycle apart as described below.

By counting the number of peaks recorded at each scanner, it is possible to

calculate within 3.2 mm (1/8 in) how high the hammer was raised for any given

stroke. It is also possible to calculate the "instantaneous" velocity at any

time by noting the time span between the peaks on the graph. The elapsed time

13
FROM

TOP SCANNER

LIGHT BEAM

POWER SUPPLY

AND CONDITIONING

LOAD CELL

POWER SUPPLY

AND CONDITIONING

FROM

BOTTOM SCANNER

OPERATOR'S

VOICE CHANNEL

FOR COMMENTS

DURING TESTING

PRECISE

TIME MARKINGS

ON TAPE

FROM FORCE LINK

FROM LOAD CELL

Figure 2-2. Instrumentation schematic diagram.

14
Figure 2-3. Photograph of test setup showing targeted safety hammer,

instrumented section of drill stem, load cell, and top and

bottom scanner opposite target. Angle frame is adjusted

to be parallel to hammer prior to test.

15

may be taken directly off the oscillograph, or more accurately with the aid of

a digital processing oscilloscope and the velocity may be obtained by knowing

the center-to-center distance between the lines on the target. The actual

procedure is discussed below.

Figure 2-5 shows graphically how the fall height is evaluated. During the up

stroke of the hammer and target, the scanner "sees" reflections or peaks on the target, starting with 1, 2, 3... 15. As the hammer returns downward, the

top scanner sees the same peaks in reverse order, 15... 3, 2, 1. The last

reflector sensed by the top scanner when the hammer is at its maximum height

becomes the reference mark for the 762 mm (30 in) fall. Point 15 then becomes

the reference point on the target. This 15th reflector from the top (which is

also the 9th reflector from the bottom) should be the point at which the hammer

impacts for a 762 mm (30 in) fall. If the last reflector sensed by the bottom scanner is not the reference point (the 15th reflector from the top or 9th from

the bottom), then the distance from the reference point to the last reflector

sensed by the bottom scanner indicates the deviation from the prescribed 7 62 mm

(30 in) fall height. For example, if the bottom scanner had read eleven full

reflections, the fall height would have been 775 mm (30.50 in). Note that the

bottom scanner starts "reading" the 3.2 mm (1/8 in) reflections as the target

accelerates downward, seeing the target bottom or Reflector 23 first. (This

illustration uses 23 light areas. The actual target used in these tests had

63 light areas.

)

The second component of the instrumentation package was the load cell located

a sufficient distance (a minimum of 10 drill rod diameters) below the anvil

(point of hammer impact). The load cell was used to measure the stress wave generated in the drill stem. The load cell has a static capacity of 178 kN

(40,000 lb) and was signal conditioned prior to recording on magnetic tape for

future reference. An indication of the kinetic energy in the drill stem after

impact may be obtained from the force-time relationship from the load cell as discussed in the next section.

2.2 TEST PROCEDURE

A typical test sequence consists of mounting the target on the hammer,

attaching the load cell in the drill stem below the anvil, and wheeling the

Instrumentation cart containing the signal conditioning, tape recorder and

power supply into position adjacent to the hammer. The two scanners mounted

on a separate angle exactly 30 in (762 mm) apart can be moved up or down on the angle frame to wherever the hammer is located during the test. The angle

frame is adjustable to take into account a sloping ground surface; the adjustment permits the angle holding the scanners to be placed vertical and parallel

to the target.

The driller proceeds with the Standard Penetration Test and data are recorded

on tape for the top and bottom scanners and the load cell for as many blows as necessary. Anywhere from 5 to 35 blows are recorded for a given set of conditions. The tape recorder also contains an open channel for voice comments

17
2

3

4

5

6

7

8

9

10

I I 12

13

14

1516

17

1819

20

21

22

23

—Target Moves Up, Stops

at 15th Reflector

1^1/8" (3.18 mm)

I (3.18 mm)

Top Scanner

Dark

30.0"

(762mm)

Bottom Scanner

Target Moves Downj

Instantaneous Velocity

Evaluated at 1 5th Reflectory

i.e., After 9 Spike Counted

On Recording

I

4

5

6

7

8

9

10

I 1 12

1314

1516

17

1819

20

21

22

23

Reflector

1

109

8

7

6

5

4

3

2

Figure 2-5. Example of how fall height is evaluated using

a targeted hammer and light beam scanners.

18
during the test. Data are taken on the tape recorder at a speed of 134. A cm/s

(60 in/s). When the data are reduced in the laboratory, the tape recorder is

played back at 4.76 cm/s (1 7/8 in/s) providing a time expansion of 32.00.

Both color and black and white photographs of the setup are taken for documentation. A photograph is also taken perpendicular to the axis of the cathead

to establish the angle the rope makes entering and leaving the cathead. This

information allows the determination of the rope contact angle leading to the

correct number of turns of rope [Kovacs, 1980],

A measurement of the cathead rotational speed is taken with a multiple range

hand held tachometer. The cathead rotational direction is also noted along

with measurements of drill stem length, hammer type and configuration, etc.

In summary, the following data are obtained during a test:

(1) Information on the physical dimensions of the drilling rig,

equipment and drill stem length, etc.

(2) Time history of top and bottom scanners noting hammer position

during the rise and fall of the hammer.

(3) Force-time history in the drill stem below the anvil.

(4) Cathead speed and rotational direction.

The use of these data and how they are reduced is discussed in the next

section,

2.3 METHODS OF DATA REDUCTION AND COMPUTATIONS

The time histories of the top and bottom scanner are played back at 1/32 of

actual speed and recorded on an ink pen oscillograph as shown in figure 2.4.

For each blow, the fall height is determined as previously discussed. Next the

bottom scanner output and output from the load cell are played back, again at

1/32 of its actual speed, on a digital processing oscilloscope. This device

permits data from the scanner and load trace to be viewed and digitized by means of an internal micro-processor. The sequence of events is shown in

figure 2.6. The top trace is the bottom scanner output and the lower trace is

the load cell output.

In figure 2-6a, the data are first displayed from a play back of the recording

tape. Two cursors are set on the bottom scanner (upper curve) as close to one cycle apart as possible at a point very close to when the hammer impact occurs. The device digitizes the analog data at any rate desired. A rate of 2000

points per second was chosen for this study. The force data (lower curve)

shows the exact point in time of impact; the cursors are always set one cycle

(0.25 in) apart prior to impact. The velocity of the hammer just before impact

is given by (data taken in customary English Units):

V = distance = 0.25 in (i)

1 t ime At

32

19
Sequence of events in data reduction and computations of the

velocity just before impact and energy values at impact in

the drill stem. Data from blow number 87, series 8.

20
In this example, At = 0.0606 s (lower right of figure 2-6b); 0.25 in = the

spacing between two light areas on the target and 32 is the time scale factor

between record and playback used to compute real time. Solution of equation

(1) for this example gives the parameter A defined as the velocity just prior

to impact of 335.3 cm/s (132.01 in/s).

The kinetic energy just before impact is computed using equation (2),

= 1/2 m V.2 (2)

= 1/2 X 42-1^ sec2 ^32. 01 m]^

386 in —

= 3160.4 in-lbs (357 J)

where Ey = Kinetic energy just before impact, the energy for velocity,

m = Mass of the falling hammer

V-j^ = Velocity of the hammer just before impact.

The known fall height of 79.4 cm (31.25 in) for this example, is then

introduced into the computer program (as parameter B in figure 2-6c). The

kinetic energy just before impact is computed using equation (2). The ratio

of kinetic energy just before impact, Ey to the potential energy, the product

of W times H, is defined as the energy ratio for velocity (or efficiency).

The energy ratio for velocity or efficiency

equation (3).

is next computed using

ER V

WH

(3)

= 3160.4 in-lb

140 lb X 31.25 in

= 0.722

where ER^ = Energy ratio for velocity (or efficiency) just before impact

W = The weight of the hammer

H = Measured fall height

For this example, Ey is shown in figure 2-6c as parameter A' and the energy

ratio for velocity is given as parameter D. For this condition, the

hammer-rope system is 72.2 percent efficient.

21
The energy from the first compression wave pulse is now calculated. First the cursors are placed on the lower trace of figure 2-6d. The left cursor is

placed exactly at the point where the force starts to increase. The second cursor is placed where the trace first becomes zero again, using the first cursor as zero force reference. The right cursor represents the time (At) when

the summation of the downward compressive force from the hammer is exactly

cancelled by the reflected tensile wave [Schmertmann and Palacios, 1979].

This is when the hammer physically separates from the anvil. This point in

time normally occurs at

At = 11 (4a)

c

Because the load cell is below the anvil by a distance AA, At is computed by

equation (4b).

At = 2(i^ - A£) (4b)

c

where i = The distance from the point of impact to the bottom of the sampler,

A£ = The distance from the point of impact to the load cell, and

c = Compressive or p wave velocity of sound in the steel drill stem.

The force-time curve is intergrated according to the following relationship

0

E = / [F(t)]2 dt (5)

^ A/Ep

where E^- = The energy in the drill rod from the first compression wave pulse,

the energy for F(t),

K = A correction factor to account for the location of the load cell

below the anvil [After Schmertmann, 1980],

K£ = A correction for length described by Schmertmann and Palacios

[1979] to account for the fact that there may be insufficient time

for the potential energy of the hammer to be imparted to the anvil

and drill stem before the returning stress wave separates the hammer

from the anvil,

E = Young's modulus of the drill rods, 0.2 TPa (29.7 x 10^ psi),

p = Mass density of the steel drill rods, 7.85 Mg/m^ (7.24 x lO""^ Ihsec/in^).

22
Figure 2-7. Correction factor to account for the non-ideal position

of the load cell and the length of drill rods. [After

Schmertmann, 1980.]

23
A = Cross sectional area of the drill rods, and

F(t) = The force-time function shown in figure 2-6d (for this example).

The intergration process is done automatically and is shown in figure 2-6e while

figure 2-6f presents the completed calculation. The intergration calculation

by the digital processing oscilloscope is accurate to within 0.061 percent. The

amount of energy for this example is found to be 364 J (3224.7 in-lb) and is

displayed as parameter "E'" in figure 2-6f. The energy ratio for the energy in

the drill rod is given by:

ER =^ =

'^'^1^-1 = .737 (6)

r WH 140 X 31.25

where ERj. = Energy ratio for F(t) or efficiency for the drill rod,

Ej. = Energy determined by means of equation (5), energy for F(t),

W = Weight of hammer,

H = Measured fall height.

For this example, the value of ERj. equals 0.737, as shown by parameter "D'".

Note that in this example the calculated energy in the drill stem is slightly

larger (which is impossible) than the input energy, i.e., the kinetic energy

at impact, by:

= 3224 7 - 3160.4 ^ ^ 2.03 percent

Ev 3160.4

Considering the non-uniform cross sectional area and discontinuities in the

drill rod presented by the load cell below the anvil, the agreement between the

kinetic energy just before impact and that obtained from the first compression

wave are quite close for this particular mechanical system. It should also be

noted that computation of energy, E^., using the digital processing oscilloscope

is sensitive to the selection of the starting point for the integration of the

force-time function (equation 5). Furthermore, the digitalization of the force

time curve, the squaring of its ordinates, and possible inaccuracies in the

load cell measurement may also contribute to the observed discrepancy.

Two definitions of energy ratio have been presented so far, ERy, (Equation 3)

and ERj. (equation 6). Note both of these definitions employ the measured fall

height for the actual blow wherein the energy is measured, Schmertmann [1980]

employs two other definitions of energy ratio based upon an assumed 76 cm

(30 in) fall. These definitions are:

Ehi

ER, . = —— (7) hi

24
and

ER, (8)

where Ej^^ = The energy just prior to Impact based upon a back calculation

of stress in the rod and solving for the required velocity

[Schmertmann and Palacios, 1979, pg. 910] then computing energy

by 1/2 m v2.

= The incident energy in the rods as determined from a graphical

intergration of the force-time relationship. For this study, the

intergration was made by calculations using the digital processing

oscilloscope. For our purposes, E-j^ in equation (8) equals Ej- in

equations (5) and (6). Schmertmann and Palacios [1979] denote E-j^

All four definitions of energy ratio are summarized in table 2-1 for

comparison. Mention of the definitions expressed in equations (7) and (8) are necessary for existing and future comparisons in the literature.

as ENTHRU.

E* The theoretical free fall energy assuming a 762 mm (30 in) fall

specified in the standard equals 475 J (4200 in-lb).

25
Table 2-1. Suininary of Energy Ratio Definitions

FALL HEIGHT j

i BASIS i Measured Fall

1 Assumed 76 cm |

1 (30 in) fall 1

1 Based on velocity |

1 just before impact I

E

V WH

1 E, .

1 ER, . = -iii

1 hi E* 1

Equation (3) 1 Equation (7) |

1 Based on intergration |

1 of force-time |

1 relationship |

ER^ =

^ WH

Equation (6)

1 E.

1 ER, =

1 1 E* 1

1 Equation (8) |

Notes: E^. = E.^ = ENTHRU

The symbols and definitions of Schmertmann [1980] in equations (7) and

(8) have been preserved in this report.

E^ = Kinetic energy just before impact.

Ej^j^ = Kinetic energy just before impact based upon a back calculation of stress in the rod and solving for the required

velocity, then computing energy from 1/2 m V^.

E, = Ej. = Energy in the drill rods from the first compression wave

pulse, the energy for F(t).

Facing page: Meas^a?ement of cathead

rotational speed duriytg the Standard

'Penetration Test. ISIote the use of

new rope and about 2.2 turns of rope

around the cathead.

26
3. PRESENTATION AND DISCUSSION OF TEST ElESULTS

The tables and figures in this section provide information on (a) the test

conditions of the four drill rig systems measured (b) operator performance and

(c) the energies delivered by the various drill rig systems as measured by the

hammer kinetic energy and force-time approaches. Following introductory com- ments about the nature of the tables and figures presented, a discussion of

the data is provided.

27
Table 3-1 presents a summary of the test conditions of the four drill rig

systems measured and the results of operator performance using the cathead and

rope method. Delivered energies of the various drill rig systems tested are presented in table 3-2 and appendix A.

As can be seen, the data for Series 1 presented in table 3-2 are examples

of the energy data obtained from the study and serve to illustrate the data

available in appendix A on Series 2 through 35.

For each series, each data point is identified by a "blow number" in Column 2.

The calculated values of the velocity just before impact Vj^, energy in the

drill rod E^., and the time interval for a round trip for the stress wave,

2 l/c are given in Columns (3), (7), and (9), respectively. These data are used to compute the kinetic energy of the hammer just prior to impact, E^, the

energy ratio for velocity (before impact) ER^, the energy ratio for F(t) (based

on the intergration of the force-time relationship), ER^., and the energy transfer ratio ETR, presented in Columns (4), (5), (8), and (6), respectively. The

energy transfer ratio is defined as

ETR = ERj./ER^ = Ej./E^ (9)

and should be <^ 1.0 as the energy measured below the anvil cannot be greater

than the kinetic energy of the hammer. For convenience and understanding, we have plotted these data for Series 1 in several ways. Figure 3-1 shows the

hammer velocity just prior to impact versus measured fall height for the Series

1 data. Hereafter, these parameters will just be referred to as "velocity" and

"fall height," respectively. Notice the variation of fall height from the prescribed 76 cm (30 in) ASTM D 1586 required standard. For these 14 data points,

the average fall is 77.1 cm (30.48 in) with a range of 8.1 cm (3.2 in). [Actually, the (same) operator for Series 1 through 18 is quite consistent as shown

in Column 5 of table 3-1. Perhaps his initial 76 cm (30 in) mark on the slip

pipe was in error, causing an average fall slightly above the standard fall.]

For these conditions of using a 1.9 cm (3/4 in) diameter old rope, and an

20.3 cm (8 in) diameter cathead revolving at 165 m/min (540 ft p/min), this SPT

hammer-system is 68 percent efficient (ER^ = .682). The efficiency would be

slightly higher if it were corrected for a 76 cm (30.0 in) fall. Had there

been 100 percent free fall, the data would follow the theoretical relationship

for a freely falling body at the top of the figure: V = i/ 2gh, where V = the

velocity just before impact, g = acceleration of gravity, and h = fall height.

Figure 3-2 shows the variation in hammer velocity with fall height and the

number of turns of rope around the cathead based on regression analysis. As can be seen, there is again scatter (as expected) in the fall height and corre- sponding velocities. (The reduced data for each blow for Series 2, 3, and 4

may be found in appendix A, table A-1).

Note that the velocity increases as fall height increases similar to the

theoretical slope and that as the number of turns increases from 1 to 3, the

velocity, and therefore kinetic energy and efficiency of the SPT hammer system

28
60

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29
Table 3-2. Detailed Measured Data and Energy Ratios for Series 1

Fall

Series Blow Vi Ev Er 2£/c Height

Number Number (in/s) (in-lbs) ERv ERr/ERv (in-lbs) ERi- (ms) (in)

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)

1 13 125.79 2869 .695 .96 2754 .667 4.356 29.5

14 131.58 3140 .729 .97 3083 .705 4.350 30.75

15 130.08 3069 .701 1.02 3136 .717 4.325 31.25

16 125.00 2834 .637 .98 2765 .622 4.369 31.75

17 124.03 2790 .643 1.03 2870 .661 4.350 31.0

18 124.03 2790 .643 .99 2776 .640 4.350 31.0

19 125.98 2878 .685 .96 2752 .655 4.344 30.0

20 125.98 2878 .669 1.01 2899 .673 4.356 30.75

21 126.98 1 2924 .685 .94 2751 .644 3.025 30.5

22 126.98 2924 .690 1.01 2937 .694 4.356 30.25

23 125.98 1 2878 .685 1.01 2929 .697 4.344 30.0

24 125.98 2878 .680 .95 2740 .647 4.356 30.25

25 125.98 2878 .685 .96 2771 .660 4.381 30.0

26 125.98 2828 .721 .99 1 2861 .717 4.363 28.5

30
150

140

130

V = (2gh|/'

o o

O 30 O O

S 120 Numeral indicates number

of data points

110

100

2 TURNS

3^" OLD ROPE

8" 0 CATHEAD @ 540fpm

CME 55

90

80

,AVG.

I t I 27 28 29 30 31 32

Figure 3-1,

FALL HEIGHT - INCHES

Hammer velocity just before impact versus

fall height for Series 1 data.

31
170 T T

Figure 3-2. Hammer velocity just before impact versus fall

height for Series 2, 3, and 4 data (least

squares fit of data in table A-1).

32
decreases. The effect is more pronounced from 2 to 3 turns than from 1 to 2 turns. This reduction in efficiency with increasing number of turns has been

observed during previous studies [Kovacs et al., 1975] and is typical for

drilling rigs equipped with a cathead and rope system for performing the SPT.

When the energy ratio for velocity ER^ = E^/WH is plotted versus fall height

as in figure 3-3, one would expect a constant value of energy ratio for a given number of turns, rope age, and cathead speed. However, figure 3-3 shows

that the actual energy ratio data are not uniform for a given number of turns

but vary as was seen in previous figure 3-2. This variation in ER^ with fall

height remains to be explained since it is recognized that the velocity determination is reproducible to within 1.5 percent depending on where the cursors

are set (Kovacs, 1979) (see discussion regarding figure 2-6). Regression

analysis was used to draw the lines on figure 3-3.

Finally, the energy ratio for velocity ER^, versus energy ratio for F(t), ERj-,

is plotted in figure 3-4 to illustrate the difference in energy ratio computed

using the kinetic energy of the hammer and the energy ratio computed using the

integration of the force-time relationship obtained from the load cell in the

vicinity of the anvil. If the data fall below the 45° line, then the energy

determined by intergration of the load cell (force-time data) is higher than

the kinetic energy. Clearly, this is physically impossible. Possible reasons

for calculating higher energy may be caused by:

(1) The load cell causes a discontinuity in the drill stem, thereby

possibly creating a false reading despite earlier theoretical

work by Gallet [1976] which indicated that the effect of the

load cell on the wave form and the blow count N was negligible.

(2) The load cell, statically calibrated, is not measuring a true

dynamic load.

(3) Experimental error in measurements of the fall height or force

in the load cell.

Tables of data similar to table 3-2 for the remaining Series 5 through 35, are presented in appendix A for reference. A discussion of the resulting summary

of the data tables and graphs for Series 1 through 35 that are useful in

further interpreting the SPT for engineering practice follows.

Because of the large amount of data obtained from the study, it was decided to

average the data contained in Columns 4, 5, 7 and 8, 9 and 10 of the data (in

tables 3-2 and those in the appendix) for the 35 series. In this way, the wide

variation in fall heights could be dealt with more easily and the available

data would be more manageable to investigate the observed trends. The results

of this effort are presented in table 3-3. It should be noted that in Columns

5 through 8, the energy ratios are given based on the energy ratio for velocity

and the energy ratio for F(t) for both the measured fall height and the assumed

762 mm (30-in) fall height. Depending upon the definition of energy ratio that

is used, the energy ratios in Columns 6 and 8 and Columns 5 and 7 will be identical provided the operator has an average fall of 762 mm (30 in). The energy

33
Figure 3-3. Energy ratio for velocity versus fall height for Series 2, 3,

and 4 data.

34
DATA FROM SERIES 2, 3, AND 4 (TABLE A-1)

SYMBOL No. OF TURNS SERIES

O 1 2

A 2 3

Figure 3-4. Energy ratio for velocity versus energy ratio for

F(t) for Series 2, 3, and 4, corrected for drill

stem length using figure 2-7,

35
ratio in Column 7, ^^\i± was computed by dividing the energy for velocity Ey

by the energy at the standard fall of 762 nim (30 in) and not according to

Schmertmann and Palacios [1979]. However, from experience gained in this

study as well as previous studies [Kovacs, et al., 1975] differences in energy

ratio up to -14.5 percent are possible when the average fall height is substantially different from the prescribed amount of 30 in. The percent difference

column for the energy ratio for F(t) based on the actual fall height and the

energy ratio for F(t) based on an assumed 762 mm (30 in) fall height is given

in Column 14. In general, the percent difference is negative indicating that

operators have a tendency to use a larger stroke (i.e. fall height) than is

required.

In an earlier study [Kovacs, et al., 1975], the energy ratio for velocity was plotted vs. the number of turns of rope around the cathead and the age of the

rope (figure 3-5). In this study, using a Mobile Drilling Company B-50 drilling rig, both old and new rope were used. The difference in energy ratio for

velocity for a particular age of rope in terms of the number of nominal turns

is negligible when compared between one and two turns but increases when

three turns are used. The difference is much more pronounced when old rope is

used because old rope tends to drape itself around the cathead causing further

retardation and inefficiency of the hammer fall. On the other hand new rope

is stiff and tends to maintain a larger radius of rope around the cathead when

the rope is released into the cathead thereby allowing the hammer to fall more

freely.

In a similar manner, data from Columns 4 and 5 of table 3-3 are plotted in

figure 3-6 for Series 1 through 18. In these particular test series, the usual

number of turns for this operator was two (actually 2.2; see notes for table

3-3). Similar behavior to that shown in figure 3-5 is noted between the energy

ratio for velocity and the number of turns and with respect to rope age. Again,

old rope tends to give a lower energy ratio than new rope. Of significance in

figure 3-6 is that the energy ratio for velocity at one turn is approximately

78 percent for this drill rig. The corresponding value for the B-50 rig shown

on figure 3-5 is only 66 percent. Thus it can be expected and it will be

shown later that different drill rigs show different relationships between the

energy ratio for velocity and the number of turns of rope around the cathead.

When the energy ratio for F(t) is plotted vs. the number of turns of rope from

column 6 of table 3-3, the result is shown in figure 3-7. The relationships

between energy ratio and the number of turns and rope age show a similar one to

that of figure 3-6. In fact, the curves for new rope are practically the same

curve.

The energy ratio for velocity is plotted vs. the energy ratio for F(t) (Columns

5 and 6 of table 3-3) in figure 3-8. If there is 100 percent energy transfer

between the hammer and the anvil, the data points should fall along the straight

line inclined at a 45° angle. However, none of the data should fall below the

36
1.0

Figure 3-5. Energy ratio for velocity versus number of turns for a Mobile

Drilling Company, B-50, rig [after Kovacs et al. , 1975].

37
1.0

0.8

>-

>-CD

0.6

S 0.4

0.2

Series 1-18

• New rope

o Old rope

CME 55

0

2 3

NUMBER OF TURNS

Figure 3-6. Energy ratio for velocity versus number

of turns for Series 1 through 18.

38
to3Ouk

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39
NOTES FOR TABLE 3-3

(1) Refer to table 3-1 for other details for a given series.

(2) In colximn 4, the nominal number of turns is given. The actual number of

turns should be adjusted according to the following schedule to account

for the actual rope contact around the cathead [Kovacs, 1980].

Series Correction to Nominal turns

1-18 Add 0.2 turns

19-27 Subtract 0.25 turns

28-31 Add 0.2 turns

32-35 Add 0.2 turns

(3) The following schedule lists the length of drill stem from the point of

impact to the bottom of the sampler and the value of the Schmertmann

correction factor for drill stem length and location of the load cell

(15).

Series Length K

1-18 39 ft (11.9 m) 1.01 .988

19 20 .5 (6.3 m) 1.01 .899

20-21 30 .5 (9.3 m) 1.035, 1.028, respectively .968

22-27 36 .5 (11.1 m) 1.02 .983

28-31 20 (6.1 m) 1.028 .893

32 10 (3.1 m) 1.13 .690

33-35 17 (5.2 m) 1.05 .850

(4) Some series are missing due to lack of data during testing.

(5) In column 12, S stands for safety hammer while D stands for the donut

hammer

40
1.0

>-

0.8 -

0.6 -

0.4

0.2 -

2 3

NUMBER OF TURNS

Figure 3-7. Energy ratio for F(t) versus number

of turns for Series 1 through 18.

41
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

ENERGY RATIO FOR F|t], ERf

Figure 3-8. Energy ratio for velocity versus energy ratio for F(t)

for Series 1 through 18 and Series 28 through 31.

42
line for the reasons discussed previously. Generally, the data are close to

the line with the exception of the four data points for the donut hammer. It

should be pointed out that some of the offset from the 45° line may be due to

differences in drill stem length because the drill stem length correction has

not been applied to individual data points but merely the correction for the

load cell location (figure 2-7). The data taken with the safety hammer (unmarked

data points) are with a drill stem length of 13 m (4U ft) while those taken

with the donut hammer are with a drill stem length of 6 m (20 ft). Examination

of the four data points obtained using the donut hammer in figure 3-8 and the

correction for the drill stem length (figure 3-12) indicates that applying the

drill stem length correction factor (see below) would not eliminate all of the

offset from the 45° line. It appears that the two different types of hammers

have different energy transfer characteristics.

In a similar manner, the data for Series 19 through 27 have been plotted in

figures 3-9, 3-10, and summarized in figure 3-11. In these particular Series,

only new rope was used and generally the data for energy ratio for velocity

and energy ratio for F(t) lie on top of each other with respect to the number

of turns of rope used by this operator. As a matter of interest, the energy

ratio for one turn for a CME 750 is the same as that for the CME 55 drill rig

(approximately 78 percent). When the two energy ratios are compared in figure

3-11, we see that most of the data fall close to the 45° line. The exceptions

to this trend are those points (Series 20 and 21) which are from a more shallow

depth of testing. Thus there appears to be a reduction in energy from the

point of impact to the bottom of the sampler in the drill stem calculation from

the force-time data. This is in accordance with theory as discussed by

Fairhurst [1961] and cited by Schmertmann [1980]. This relationship is shown

in figure 3-12 by the dashed line. This relationship is for the case when the

load cell is at the ideal position at the point of impact. To apply the length

correction, one merely divides the energy Ej. (or E^) by Kj^, the drill stem

length correction factor from figure 3-12. An example of the correction is

given in the paragraph below. In this graph, the length of the drill stem

(from the point of impact to the bottom of the sampler) is plotted vs. the

energy in the rods as determined from F(t) divided by the theoretical available

energy, E* [475 J (4200 in lbs)]. It can be seen that at short drill stem

lengths, on the order of 1.5 m (5 ft), that the maximum energy that is available theoretically is only 40 percent and gradually increases to 100 percent at

approximately a depth of 15 m (50 ft).

The data for Series 28 through 31 for a CME 55 drill rig with a donut hammer

and old rope only, are shown in figures 3-13a and 3-13b in terms of the energy

ratio for velocity vs. the number of turns and the energy ratio for F(t) vs.

the number of turns, respectively.

This figure illustrates the importance of the number of turns on the energy

ratio but more importantly reemphasizes the influence of hammer geometry on the

energy transmission characteristics discussed earlier. When the drill stem

length correction is applied to the energy ratio for F(t), ERj-, the dashed line

43
1.0

0.8

2 0.6

usual

CD

0.4

0.2

Series 19-27

New rope

CME 750

1 1

1 2 3

NUMBER OF TURNS

Figure 3-9. Energy ratio for velocity versus number of turns

for Series 19 through 27. Number beside points

indicate number of data points.

44
1.0

0.8

cr 0.6 -

0.4 -

C9

0.2 -

0

Series 19-27

New rope

CME 750

usual

1

1 2 3

NUMBER OF TURNS

Figure 3-10. Energy ratio for F(t) versus number of turns

for Series 19 through 27.

45
Figure 3-11. Energy ratio for velocity versus energy ratio

for F(t) for series 19 through 27.

46
10

20

^

30

CO

C9

40

iiJ 50

60

70

80

Theoretical Maximum

Efficiency For

AW Rod

S-hammer

Sampler

0.2 0.4 0.6 0.8 Ej/E*= EFFICIENCY OF SYSTEM

\- 9

toa

12 S

CO

15 ^

18

21

- 24

1.0

Figure 3-12. Theoretical relationship between efficiency of the hammer

system Ej^/E*, versus length of drill stem for AW rod

[After Schmertmann, 1980], Relationship is for the case when the load cell is at the ideal position at the point

of impact.

47
1.1

USUAL

0.8

0.6

0.4

ERrlwith both

corrections)

0.2

cell correction only)

SERIES 28-31 CME 55

DONUT HAMMER & OLD ROPE

0

1 2 3

NUMBER OF TURNS

Figure 3-13. Energy ratio versus number of turns for Series 28

through 31.

48
in figure 3-13 results. The remaining difference (the ordinate) between the

two curves, ER^ and the corrected curve for ERj-, must be due to hammer geometry. In contrast, compare figure 3-9 and figure 3-10 for the safety hammer

data. When the drill stem correction factor is applied to the energy ratio

for F(t) (K£ ranges from 0.9 to 0.985), on figure 3-10, and the corrected

curve is compared with the energy ratio for velocity curve, the two curves are almost identical.

Data for Series 32 through 35 for a CME 45 drilling rig using old rope with a donut hammer are shown in figures 3-14a and b where the energy ratio for velocity and the energy ratio for F(t) are plotted vs. the number of turns, respectively. It is significant to note that in figure 3-14a the energy ratio

for velocity for one turn is similar to the other CME rigs studied; they are approximately 80 percent efficient. Note the very low efficiencies for this

donut hammer when one compares the energy ratio for F(t) vs. the number of

turns on figure 3-l4b. One might expect the family of curves to be increasing

upward as the length of the drill stem increases. When these data are plotted

in terms of energy ratio for velocity versus the energy ratio for F(t) in

figure 3-l4c, one sees that the data points plot significantly above the 45°

line. The location of these data points indicate that the hammer is not

delivering to the drill stem all of the kinetic energy that was available

just before impact.

When all of the average data are shown in terms of the energy transfer ratio versus a parameter related to the length of the drill stem, it becomes obvious

that the shape of the hammer has an important influence on the amount of energy

transferred to the sampler itself. The relationship is shown in figure 3-15

where we have plotted the ratio of the energy ratio for F(t) divided by the

energy ratio for velocity. We could call this ratio the energy transfer ratio.

It essentially represents the efficiency of the energy transfer mechanism

between the hammer energy just prior to impact and that obtained from the

energy in the drill stem, after impact. This ratio is plotted versus ll/c, the

measured time it takes for the stress wave to travel from the point of impact

to the bottom of the sampler and return to the anvil and separate the hammer

from contact with the anvil. Actually this time is the time it takes for the

wave to pass downward through the load cell, reach the end of the sampler, and

return upward as a tension wave through the load cell cancelling out the energy

still being imparted to the drill stem by the hammer. This relationship of

force-time was previously shown in figure 2-6. In figure 3-15, all the data

are plotted with symbols differentiating the number of turns of rope used

around the cathead as well as the hammer-type. Numbers beside each point

indicate the number of data points that was averaged to obtain the particular

point. The significant difference between the energy transfer mechanism of the

safety hammer as shown by open data points compared to the lower energy transfer ratio of the data from the use of the donut hammer can be clearly seen. The sleeve enclosed safety hammer appears much more efficient than the donut

hammer in transferring its kinetic energy before impact to the drill stem F(t)

49
1 2 3 NUMBER OF TURNS

1.0

0.8

^ 0.6

eeoLl_ o

i 0.4 >

0.2 -

(b)

Series 32-35

Old rope CME 45

3?

-o..^(z=17')

|z= 101 -o19

Numeral indicates number

of data points

z = rod length 12 I3 4 NUMBER OF TURNS

Figure 3-14. Data for Series 32 through 35. (a) ER for velocity versus number of turns, (b) ER for F(t) versus number of turns,

and (c) ER for velocity versus ER for F(t).

50
1.2

1.1

1.0

0.9

0.8 -

0.7 -

0.6

0.5 -

0.4

10

OLD ROPE NEW ROPE

25 olo a20

piu,10 10Oo5^„

A18

25

^13

14 ^

10

Hammer:

Safety '

Donut , • 6

08

A31

5

7

19

No of data /

points averaged

No. Of

Turns

12

3

4

L_

Hammer Type

Donut Safety • o

A

S7

2 3

MEASURED 2^/c (msj

Figure 3-15. Energy transfer ratio, ERj./ERy versus the measured

time for the return wave, 2i/c.

51
below the anvil. It should be pointed out that the data presented in

figure 3-15 has been corrected for drill stem length by using figure 3-12.

Previously, the hammer geometry has been suggested as the primary cause for

the differences between the energy ratio for F(t) with corrections and the

energy ratio for velocity. However, Hanskat studied the effects of hammer

shape with the wave equation and showed that the shape of the hammer alone

made no significant difference. Because the anvil type varies greatly between

hammers (small for safety hammer and large for the donut hammer), this component of the hammer assembly may be the primary cause of energy differences.

This observation requires experimental verification. All the known energy

ratios for various types of rigs determined to date under the operator's usual

working conditions are presented in table 3-4. In many instances, the data

are incomplete as only one of the three definitions of energy ratio is given.

In table 3-4, Column 1 describes the manufacturer and model number as well as the hammer type. The number of turns normally used, if known, is given in

Column 2. Because drill stem length plays an important part of the energy

reaching the sampler, data is given for this variable in Column 3. Of the

three energy ratio definitions shown in table 3-4, only that defined by the

energy for F(t) divided by the product of the hammer weight times the measured

fall weight gives a true indication of the energy efficiency reaching the

sampler. This energy ratio is presented in Column 5. A similar energy ratio

is presented in Column 6 where the energy for F(t) is divided by the standard

energy of 475 J (4200 in-lb). Any numerical difference between Columns 5 and

6 reflect the fact that the measured fall height was not the prescribed 30 in

(762 mm) fall height. Cases in which the value in Column 6 is larger than the

value in Column 5 indicates that the actual fall height was greater than 30 in

(762 mm).

It should be pointed out that the data from Schmertmann and Smith [1977] are based on the integration of oscilloscope records of F(t) while those data from

Schmertmann [1980] are average values taken directly from the Binary Instruments' SPT Calibrator. The data in Column 6 from this study were determined

by dividing the energy for F(t) by 475 J (4200 in-lb).

At this point, the authors wish to introduce the concept of the National

Average Energy (NAE). The average energy for a given drill rig model is the

average energy for F(t) determined by the statistically significant number of

drill rigs of that particular model. When the data are averaged, based on the

number and availability of drill rigs used throughout the United States, then

the National Average Energy for all the drill rigs that are used for the

performance of the SPT under usual operating conditions will be known. Because

there are approximately 37 drilling rig models used in the United States, a significant amount of data will have to be accumulated and a statistical

analysis performed before the NAE can be proposed to the profession. The NAE

would be a common energy that could be used as the energy standard for

performing the SPT. Using a common energy should allow reproducible and

consistent blow counts among different drill rigs (see figure 3-16) at the same site regardless of the details used in performing the test. The NAE of

52
Table 3-4. Tabulation of Energy Ratios to Date for Operator's Usual Testing Conditions

Num be r Koa of Le ng t h Ev/WH ^r/WH V.I J. •^i/E* HsmniGr TypG Turns \ i ^

C FR C FR J ~l

(2^ \ ^ J \^

}

V, ^ / ('SI ^ 3 ; Cfi") V D ; \ ' }

Mobile i. i\j u J. J. c: R-50 jj J \j 0 .75 8 .66 i\ "J V d o cu di.* \ X. y / J \ 1 .75 g .67 Mou T"AnP

2 .75 8 .51

L L\J U -L X C O -/\J 0.75 8 .67 1.75 8 .59 old rope

2.75 8 .38

3 .75 8 .25

1 .75 .58 (old rope

)

CME 45 3? 25-35 .67 C p Vim PT'trnann JinH 3? 25—35 .70 Cml rh r 1 977

1

rMF V^i ' ' 4SR ^ JJ 4? 25-35 .50 3-4 25-35 .56

iidyilcw ±.\J\j\J 3? 25—35 .45

"Pail -I no- 1 ^nn 7 £. J 3 J . 3HSA

nvrp A ^ 0? A J J J .52

"1? ^ -J J _) .53 ( nul r»n T"riF»P 1 3 .51 1 nvl An T"rir»p 1

ft7 raixing xjuu wire .34SA mech • AC K.e r n,"' Z V ^ / .30SA R-rnun T 1 QftOl ^ 9

9 i9 .53 ^T'TAra't'P L J, X V d L. C 1 riTTTTTii 1 i 111 III 1 11 1 IX^CL r'at"'f rtn no D 1 ± e D~ J ^ ^ ^ bu t i

;

SQ .33

L-rlci J J \iJ

)

•3 IDO .76

L-rl£j 33 \^

)

Z 1

D

.44 noDixe D J J Ai V V ^3 / 9 .64 Mobile B-80 (S) SD (1) 34 .50 Schmertmann [1980] (2) Mobile B-80 (S) 2 14 .41 Private Communication

ijncj H- J 111U.U LJug V '5 / 2 38 .60 Usual number of turns

•

CME 45 mud bug (S) (3) 38 .55 (same rig) CME 45 mud bug (S) 38 .30 Steinberg [1980] (2

)

13.5 .51 Private Conununica t ion

2 13.5 .36

2 13 .5 .45

2 13.5 .71 Operator D

2 13 .5 .60 Operator F

Joy b— iz \u) L .42 \j L a, K.\J i. n. i 19 S .33 UptrLdLUL \j MODi±e b—J't bu (. i

;

17 9 i / . Z .46 Ot^pt" a tr^T" T MoDlie B—Di \u) 10 S T9 0UptrLdLUI. 1^ o T* a fr* T"

rt. A

oL IT13.3S .40 DrtPTafTiT* R

Z

113.3 S S .37 nnpTaf"nT" C CME 55 (S) 2 .2 .by A7 .DO This study (old rope)

z • z

7 A .DO . AQD -? 9z • z9 40 .73 .70 .71

9z • 9z 40 .72 .73 .75

9 9 40 .76 .80 .81 This s tudy ( new rope)

9z • z9 40 .74 .75 .77

2 .2 40 .74 .72 .73 CME 750 (S) 2.75 20.5 .68 .65 .62 This study (new rope)

2.75 30.5 .68 .59 .63 2.75 36.5 .68 .64 .65

2 .75 36.5 .69 .69 .70 CME 55 (D) 2.2 20 .77 .55 .57 This study (new rope)

2 .2 20 .79 .53 .55 CME 45 (D) 2.2 10 .75 .27 .31 This study (old rope) 2.2 17 .3 .75 .42 .46

(1) SD denotes Saf e-T-Driver ; S denotes safety hammer, D denotes donut hammer.

(2) Corrections K and Kjj included.
Acker M-2

CME 45

CME 45B

CME 55

CME 65

CME 550

CME 750

Joy B-12

Meyhew 1000

Failing 1500

Mobile B-33

Mobile B-34

Mobile B-61

Mobile B-80

+ + V oo A DO

o

+ Brown (1980) Priv. Comm. o Schmertmann & Smith (1972)

A Scbmertmann (1980) Priv. Comm.

- Steinberg (1980) Priv. Comm.

V This Study

A

o o

A

_i

o ovB

Data Include Donut and

Safety Hammers plus the Safe-T-Driver.

Data Corrected to Represent

Maximum Theoretical Energy

Using Figure 9 - 12

0.1 0.2 0.3 0.4 0.5 0.6 0.7

ENERGY RATIO FOR F(t), ER. = E./E*

0.8 0.9 1.0

Figure 3-16. Summary of data to date of energy ratio for F(t),

ERj^, for thirteen drilling rig models.

54
course, should be comparable with the past so as not to obviate all our empirical correlations with the SPT blow count. Figure 3-16 presents the first

attempt to present the energy ratio for F(t) based on an assumed fall height

of 762 mm (30 in) for drill rigs tested to date with the information known to

the authors. Typically, the data appear to range from 40 to 75 percent.

Since the energy ratio for F(t) depends upon the hammer type and drill stem

length, it is important to plot the data with respect to the energy ratio for

F(t) versus the depth for each individual model drilling rig. The "depth" is

actually the length of the drill stem between the point of impact and the

bottom of the sampler in the ground. From figure 3-16, we see that the CME 45

and CME 55 drilling rigs have five and six data points, respectively. These data

have been replotted on figures 3-17 and 3-18, respectively. The theoretical

maximum energy available for the safety hammer and AW rod from figure 3-12 is

also shown by the dashed line in these two figures.

Finally, it is important to look at the drill rig operator's performance

characteristics as well. Data given in table 3-1, Columns 5 and 6 are plotted

on figures 3-19a and b, respectively, in terms of the average fall height versus the number of turns of rope around the cathead. In most cases, the

drill rig operator produced a fall over the required 762 mm (30 in) fall and

sometimes by a substantial margin. In this figure, it is apparent that as the

number of turns increases from one to 4 turns, the average measured fall height

decreases. In addition, we can see that the variation in fall height as measured by the standard deviation (figure 3-19b) increases as the number of

turns goes up. This graph, along with figures like 3-5 appear to indicate that

a nominal two turns of rope around the cathead is the most reasonable number to use in terms of energy ratio and the ability of the operator to achieve the

required 762 ram (30 in) fall height.

A variation in fall height and the standard deviation was found during this

study for drillers who perform the standard penetration test (table 3-1 and

figure 3-19). To illustrate how experienced and inexperienced drill rig operators perform the standard penetration test using either a safety hammer or a donut hammer, the data from the first series for each of the four drill rigs

tested in this study was plotted in figure 3-20. In figure 3-20 the fall

height variation versus the blow number for the usual way in which the operator

performed the SPT is presented. The data collected is from the first time that

this individual operator was asked to run the SPT for this study. Depending

upon the operator, the variation of fall height was considerable as shown by

the four curves in figure 3-20. On the right side of each graph, the average

and standard deviation are shown. With the exception of series 19, most of

the data points are above the 762 mm (30 in) required fall height. Is this

data typical? If one were to plot the fall height versus the blow number of

the series data contained in this report, similar trends would be shown.

55
1 1

^^^^

^

1 1 —Theoretical

\

\

\

\

* \

\

\

-

Old rope No. of turns

\

\

o 1 \ A 2

o 3

V 4

1

1

1 • 0 0.2 0.4 0.6 0.8 1.0

ENERGY RATIO FOR F|t], ERj

Figure 3-17. Energy ratio for F(t), ER^, versus drill stem

length for the CME 45 drilling rig.

56
10

£ 20

CD

D D

30 Rope age

Old New No. of turns

o • 1

40 A 2

3

V T 4

50 1 1

0 —*

0.2 0.4

Theoretical

\ J

\

\

v

\

D - indicates donut hammer

0.6 0.8

ENERGY RATIO FOR F|t), ERj

1.0

Figure 3-18. Energy ratio for F(t), ER-j^, versus drill stem

length for the CME 55 drilling rig.

57
Symbol rig o CME 55 ^ CME 750 ATV ° CME 55 V CME 45

1 L_

1 2 3 NUMBER OF TURNS

a

z

00

4.0

3.5

3.0

2.5

2.0

1.5

1.0 -

0.5 -

Symbol oA

V

I

1

rig CMG 55 CME 750 ATV CME 55 CME 45

2 3 NUMBER OF TURNS

Figure 3-19. Drill rig operator's performance as measured by the

(a) fall height and (b) fall height standard

deviation versus number of turns data.

58
BLOW NUMBER

r0

35.0

32.5 h

30.0

27.5 h

35.0

32.5

30.0

27.5 h

10 20

"1 1 30 40

Series 1 (Stationary sampler]

o

Avg

o

Series 19

Series 32

o

Avg

o

Figure 3-20.

10 20

BLOW NUMBER

30 40

Variation of fall height during the performance

of the SPT by four experienced drill rig

operators under their usual test setup .

59
r

0

35.0 -

32.5 -

30.0

BLOW NUMBER

10 20 30 —

40

Inexperienced Operator

(Stationary sampler)

a

Avg

Experienced Operator

(Stationary sampler] — G ^

Avg — o

35.0

32.5

30.0

Experienced Operator

35.0

32.5

30.0

27.5

- continued from above

10 20

BLOW NUMBER

30 40

Figure 3-21. Variation of fall height during the performance

of the SPT [After Kovacs et al. 1975].

60
This conclusion is confirmed by data from an earlier study [Kovacs et al.,

1975] which have been replotted in figure 3-21. The top curve represents an inexperienced operator who had a significant variation in fall height but on

the average was very close to 762 mm (30 in). In fact he did better than the

experienced operator's performance as shown in the second graph from the top

in figure 3-21. In both of these latter two cases, a stationary sampler was used. This was not the case for the third set of data on figure 3-21 where an experienced operator performed 57 blows using a pin guided 63.5 kg (140 lb)

hammer. Perhaps the gradual way in which the fall height varied with blow

number represents the continuous penetration of the sampler into the ground

during testing and the shifts in fall height represent the operator's change

in hand position on the rope as penetration increases. This may explain why

the operator was able to achieve a nearly perfect 762 mm (30 in) fall from blow

40 to blow 57 for this operator. The sampler was hardly moving at all. Based

on the ability of the experienced operators to achieve a 762 mm (30 in) fall,

it appears that a nominal two turns of rope around the cathead to be the most

reasonable number to use in terms of the energy ratio and the ability of the

operator to achieve the required 762 mm (30 in) prescribed fall height.

61
I

Facing page: Energy Mea&urement

Ins trumentation Si} stem

n

62
4. SUMMARY AND CONCLUSIONS

Geotechnical engineers in the United States commonly use the Standard

Penetration Test in subsurface investigations for routine foundation design.

It has been said that perhaps up to 80 to 90 percent of the routine foundation

designs are accomplished by the use of the SPT"N"value. Almost all site investigations in some areas of the U.S. involve the use of the SPT. Drill rig

systems (drill rig, rope, hammer, drill rod, operator, etc.) can reproduce the same blow counts with depth at a given site. However, as noted by the variation in delivered energy among drill rig models in figure 3-16, wide variations

63
In blow count would be expected when different drill rig systems are used.

Despite efforts to standardize more details of the SPT procedure, variability

between tests is inherent under present guidelines. Consequently, a necessary

prerequisite for the continued use of the Standard Penetration Test is an improvement of its reliability, i.e., its ability to reproduce blow counts

among different drill rigs under the same site/soil conditions.

A field measurement system and procedure which measures the energy delivered

by a drill rig system was developed and used to study the factors which affect

delivered energy (see section 2). In addition, four definitions of energy

ratio have been presented in this report (table 2-1) to establish a common

terminology for others making comparisons of energy data from the SPT in the

literature. One pair of energy ratios is based on the measured fall height

while the second pair of energy ratio definitions is based on an assumed fall

height of 762 mm (30 in). The energy ratio can be calculated from the velocity

of the hammer just prior to impact or from integration of the force-time

relationship in the drill stem as described in section 3. Schmertmann and

Palacios [1979] presented an excellent argument for the use of the energy ratio

based on integration of the force-time relationship since it is the force in

the drill rods at the sampler that causes penetration. With respect to which

fall height to use (actual versus 762 mm (30 in)), for the computation of

energy ratio, it should be pointed out that the validity of assuming a 762 iran (30 in) drop is not very important. Selection of the fall height merely

establishes a reference energy from which actual energies can be compared. The

456 J (4200 in-lb) energy seems to be the logical choice because of ASTM D 1586

procedures. The next question that should be addressed is how valid is the

assumption of a 762 mm (30 in) fall height.

A variation in fall height and the standard deviation for this measurement was

found during this study for drillers who perform the standard penetration test

(table 3-1 and figure 3-19). Depending upon the operator, the variation of

fall height was considerable as shown by the four curves in figure 3-20. Based

on the ability of the experienced operators to achieve a 762 mm (30 in) fall,

it appears that a nominal two turns of rope around the cathead would lead to

the best results in terms of the energy ratio and the ability of the operator

to achieve the required 762 mm (30 in) fall height.

If the measured fall height and the assumed fall height of 30 in (762 mm) are identical then both energy ratios for F(t), ERj. and ER-j^ will be identical. The

influence of the wide variation in fall height (table 3-1 and figure 3-19) on

the difference between the energy ratio for F(t) based on the measured fall

height and the energy ratio for F(t) based on an assumed 30 in fall height can

be seen on table 3-3 in Column 14. The average value of the percent difference

(excluding Series 13 which is somewhat artificial in that four turns of rope are hardly used in production Standard Penetration Tests) is -'3.2 percent with

a standard deviation of 4.1 percent. If the average of these data where the

operator performed the test using the usual number of turns of rope is taken,

the average would be -3 percent and the standard deviation 3.7 percent. These

numbers are within the expected range of variation of routine testing and one

64
may conclude that on the average, the use of either definition of energy ratio

may be acceptable in engineering practice. However, it should be emphasized

that the data in series 28-35 were well above this average value. This difference may be due to the operators themselves. Their average values of fall

height were substantially greater than the required 762 mm (30 in). Therefore

if either definition of energy ratio is to be used or if a 762 mm (30 in) fall

is assumed it may be appropriate to measure a drill rig operator on a timely

basis to see how he is performing the SPT with respect to his average fall

height.

Based on this study, it is recommended that additional data be obtained by

measuring the energies slightly below the anvil and above the sampler versus depths for the different types of hammers that are presently used in engineering practice so that data like that shown in figures 3-17 and 3-18 may be

obtained for as many drill rig models as practical. Further, it will be

necessary to obtain data on a sufficient number of similar drill rigs to

substantiate whether a given drill rig model gives essentially the same energy

regardless of the drill rig operator. From the data presented in this report,

it appears that the different model drill rigs tested give different energy

ratios. The variation in energy ratio depends on the definition used and the

drill stem length under which the energy measurements were made. When energy

measurements are made with drill stem lengths on the order of 13 m (40 ft) then

the energy ratio for velocity and the energy ratio for F(t) are essentially

identical for the safety hammer (figure 3-12).

Using a safety hammer at a depth of approximately 13 m (40 ft) results in

about 100 percent energy transfer from the hammer to the drill rods as shown in

figure 3-4. Although the energy ratios for velocity are substantially lower

than freefall, the hammer essentially transferred to the drill rods all of

the kinetic energy available just prior to impact as shown by the one to one relationship between energy ratio for velocity and energy ratio for force seen

in figure 3-4. This relationship is essentially independent of the fall height

since the two fall height terms cancel. Thus, figures similar to figure 3-4

provide an indication of the efficiency of the energy transfer mechanism

between the hammer and the anvil to the drill stem.

If the energy transfer ratio, ERj./ERy is plotted versus the measured time for

the return wave, 2£/c, the strong influence of the hammer type on the energy

transfer mechanism between the anvil and the drill stem also can be seen (figure 3-15). Based on the limited data presented on figure 3-15, it appears

that the safety (sleeve enclosed) hammer is more efficient in transmitting the

available energy through the drill stem than the donut hammer. If further

research confirms this conclusion, the correlations of SPT penetration resistance values with geotechnical engineering parameters may have been influenced

since the invention of the safety hammer in the early 1970 's.

65
Finally, this study provides further evidence of the wide variation in the

measured delivered energies using various drill rig systems. The influence of

numerous mechanical and human factors on the measured delivered energies has

been demonstrated.

Facing page: Operator performing the

Standard Penetration Test using a safety

hammer and oloc'kwise rotation of the

cathead.

66
#^ ...

5. .ACKNOWLEDGMENTS

The writers wish to thank the four owners and operators of the drill rigs

tested in this study for their time and inconvenience. In addition,

R. E. Brown of Law Engineering Testing Company, J. H. Schmertmann of

Schmertmann and Crapps, Inc., and S. B. Steinberg of Soil Testing Services,

Inc. contributed to the information in table 3-4 regarding energy ratios for

various drilling rigs. Finally, the writers wish to acknowledge with special

thanks those individuals who provided critical reviews: B. J. Douglas,

67
L. L. Holish and J. H. Schmertmann and the two NBS reviewers, N. J. Carino and

J. Harris. A. I. Johnson, S. B. Steinberg and C. 0. Riggs also reviewed the

manuscript and their effort is appreciated.

68
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,

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69
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70
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71
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72
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73
1
APPENDIX A

Tabulation of Data

A-1

Table A-1. Results for Series 2, 3, and 4

tall

Series Blow Er 2J6/C height 1 Numbe r Number Number (in/s) (in-lb) ERy ERf/ERv (In-lb) ERr (ms) (In) of Turns

(1) (2) (3) 1 (4) (5) (6) (7) (8)

• (9) (10) 1 (11)

2 27 126.98 1 2924 .714 .972 2842 .694 3. 156 29.25

2 28 140.35 3572 .785 1.034 3692 .811 4.350 32.50

2 29 136.52 3380 .818 1.011 3531 .827 4.338 30.50

2 30 133.78 1 3246 .786 .974 3161 .765 4.338 29.50

2 31 137.46 3427 .790 1.049 3597 .829 4.338 31.00

2 32 136.52 ! 3380 .798 1.018 3439 .812 4.363 30.25

2 33 126.98 2924 .690 1. 128 3296 .778 4.356 30.25

2 34 134.68 3289 .777 1.025 3373 .797 4.356 30.25

2 35 136.99 1 3403 .778 1.027 3496 .799 4.363 31.25

2 36 136.05 1 3357 .799 1.041 3494 .832 4.350 30.00

3 37 125.79 2869 .707 1.007 2891 .712 4.350 29.00 2*

3 38 136.52 3380 .779 .980 3314 .764 4.350 31.00 2 3 39 132.01 3160 .752 .886 2800 .667 4.369 30.00 2 3 40 130.72 3099 .738 .986 3055 .727 4.363 30.00 2 3 41 129.45 3039 .724 .918 2791 .664 4.356 30.00 2

3 42 133.78 j 3246 . 742 .947 3073 .702 4.381 31.25 2 J

1. "3 4J 1 jU. / I Ton O Q "7 juy 1 JU . / J Z 3 44 134.68 3289 .746 .798 2626 .595 4.356 31.50 2 3 45 129.45 3039 .730 .871 2648 .636 4.388 29.75 2 3 46 133.78 1 3246 .754 .867 2813 .653 4.369 30.75 2 4 47 111.11 2239 .561 1.001 2241 .562 4.388 28.50 3 4 48 109.89 2190 .554 .958 2099 .531 4.406 28.25 3 4 49 98.04 1743 .449 .871 1520 .391 4.413 27.75 3 4 50 108.40 2131 .529 1.000 2128 .529 4.394 28,75 3 4 51 111.42 2251 .527 .910 2047 .479 3.056 30.50 3 4 52 107.24 2086 .497 .903 1885 .449 4.394 30.00 3 4 53 108.70 2143 .552 .868 1861 .479 3.063 27.75 3 4 54 109.59 2178 .536 .951 2068 .509 4.406 29.00 3 4 55 112.99 2315 .538 .887 2053 .477 4.388 30.75 3

4 56 112.36 2289 .541 .934 2139 .505 4.394 30.25 3

* Denotes operator's usual number of turns used in SPT.

CME 55, 3/4" old rope at 540 ft/min cathead rotational speed and clockwise rotation.

A3
Table A-2. Results for Series 5, 6, and 7

Fall Se ri 6S Blow V

.

1 F E*

•^r

711 /r tl Q 1 ^ Numbe r NurobG r M 1 1 m V\ o T" IM UUi UC 1 V ±11/ a J 1 (in-lb) FR FR /FR* < in-1 h

1

ER* (ms ) \ in ) of Turns

( I \^

)

f 3^ (6) ( 7

) ("9") MM

sJ 135. 14

s -JO 136.05 1 3357 . 834 0. 977 3277 . 814 4. 35b 23 . 7 5

11 J SQ 137.93 1

t; AO 1 J u . ^ ^ 1 3380 .805 0. 963 17 S S 77 S 4. 406 10 on 11 Js U 1 137 . 93 3450 . 789 1.011 3490 . 798 4 17 S 11 7 S 11 f\0 \J £. 1 J . / o 1 3246 • 757 0. 944 3065 7 1 S 7 Q 7 S 10 fil

1 36 . 99 3403 . 778 0. 931 3168 . 724 3. 069 11 7 S i Js AAUH 1 34 . 68 1 3289 . 790 1.012 3330 7QQ 4. 381 i.y 7Q . 71 JS 1

c; J ASD J i

1 J17/ . H U 1 3427 • / y v 0.996 1A 1

1

7Q1 10 7 '^ I1 J AAu u i1 J^SJ . JSQ7 1 m4 . 794 1 . 003 3344 7 Qfi 4 4nn 10 00 1 D A7 1 "ifi ns 1 J J J / . 767 1 . 006 3378 A 17 S 11 7 S D Aft DO 1

1 t.?Q7 . (T^ U J 1 30 1

9

. 750 0. 959 2896 1 7(1 A 17 S 7 S D AQ i

1 J19^ . RQO 7 1 1701 .709 . OH 7 Q 1 1 17 ; S 7 0 70 1 9 S 7 1 1 ^ O . il 1 1 ? 1 717 i1 . 018 VJ JO inQ 7 . / DO A 17 S )L

6 71 130.72 1 3099 .741 0.952 2952 .70b 4.375 29.83 2

6 72 130.72 1 3099 .714 1.014 3142 .Ilk 4.494 31 . 00 2

6 73 130.29 i 3079 .727 0.975 3001 .709 4.463 30.25 2

6 74 132.01 1 3160 .743 0.943 2980 .701 4.413 30.28 2

6 75 129.87 1 3059 .699 1.025 3133 .716 4.556 31.25 2

6 76 128.62 1 3000 .705 0.992 2975 .700 4.525 30. 38 2

7 77 104.17 1 1968 .481 0.926 1822 .445 4.388 29.25 3

7 78 112.68 1 2302 .560 0.928 2135 .519 4.400 29.^:7 5 3

7 79 110.19 i 2202 .516 0.903 1989 .466 4.375 30.50 3

7 80 107.53 1 2097 .521 1.010 2117 .526 4.5b9 28.7 5 3

7 81 105.54 1 2020 .525 0.993 2006 .521 4.544 27.50 3

7 82 105.54 1 2020 .493 0.923 1865 .455 4.425 29.25 3

7 83 115.94 1 2438 .526 1.027 2503 .540 4.538 33. 13 3

7 84 106.67 1 2063 .508 1.003 2069 .510 4.413 29.00 3

7 85 106.38 i 2052 .493 0.991 2034 .483 4.383 29.75 3

7

• 86 107.53 i 2097 .516 0.995 2087 .514 4.388 29.00 i

* The computed energy in column 7 needs to be multipuled by a correction factor (figure 2-7) of 1.01 to take into account the location of the load cell relative to the anvil. As a result, the values of ER^ and ERj-/ERy also increase accordingly.

Denotes operator's usual number of turns used in SPT.

CME 55, 3/4" old rope at 684 ft/min cathead rotational speed and clockwise rotation.

A4
Table A-3. Results for Series 8

Fall

1 Series DlOW *

In./

C

height Numbe r

1 Number Numbe r (, m/ s

;

(, In-ib ,' ERv ERp/ER^ ( in-lb; ERr Cms; C in; of Turns

1 \ ^ ) (.6; (, /

;

(, y

;

' ^ ( iu; (.11;

1 Q

1 o

ft? i • Ui J 1 du 7 0 0 3225 7 J 7 31.25 2**

1 Si oo ion 7 0 7 0 ^

1 . 048 7 t; 7 30 . 62 2

1 8 89 132.45 3181 . 748 1 nriH 7 SA 4. 425 30 . 38 2

1 8 90 136.05 3557 .780 0.933 3302 .767 4.450 30.75 2

1 8 91 132.89 3203 .720 0.994 3182 .716 4.406 31.75 2

1 8 92 132.89 3203 .735 0.909 2910 .668 4.375 31.12 2

1 8 93 129.87 3059 .699 1.009 3U86 .705 4.506 31.25 2

1 8 94 132.45 3181 .757 1.103 3507 .835 4.556 3U.0U I

1 8 95 131.15 3119 .702 0.986 3077 .692 4.538 31. 7j 2

1 8 96 129.03 3019 .696 1.052 3175 .731 4.488 31, OU 2

1 8 97 131.58 3140 .748 0.917 2879 .685 4.363 30.00 2

1 8 98 130.29 3078 .712 1.053 3241 .750 4.413 30.88 2

1 8 99 127.80 2962 .664 1.009 2990 .670 4.431 31.38 2

i 8 100 131.15 3119 . 735 1.045 3258 .769 4.575 30.25 2

1 8 101 130.72 3099 .700 0.922 2860 .646 4.400 31.62 2

1 8 102 129.87 3059 .694 0.951 2908 .659 4.350 31.50 2

1 8 103 129.87 3058 .696 0.974 2979 .67a 4.463 31.33 2

1 8 104 134.23 3267 .772 0.977 3259 .770 4.369 30.25 2

i 8 105 131.15 3119 .704 1.043 3253 .735 4.4^4 31.62 /

1 8 106 132.01 3160 .746 1.075 3401 .803 4.463 30.25 2

* The computed energy in column 7 needs to be multlpuled by a correction factor (figure 2-7) of 1.01 to take into account the location of the load cell relative to the anvil. As a result, the values of ERj- and ERj-ZER^ also increase accordingly.

** Denotes operator's usual number of turns used in SPT.

CME 55, 3/4" old rope at 468 ft/min cathead rotational speed and clockwise rotation.

A-5
Table A-4. Results for Series 9

1 Series Blow

(in/s)

1 Ey E* height Number 1

1 Number Number 1 (in-lb) ERv ERr/ERv (in-lb) ERr (ms) (in) of Turns 1

1 (1) (2) (3) 1 (4) (5) (6) (7) (8) (9) (10) (11) 1

1 9 107 134.68 1 3289 .847 1.053 3463 .391 4.913 27.75 2** 1

1 9 108 133.33 1 3224 .740 1.041 3353 .770 U.llb 31. 12 2 1

1 9 109 135.59 1 3334 .759 0.986 3290 .749 4.681 31.38 2 i

1 9 110 136.52 1 3380 .788 0.970 3278 .765 4.681 30.62 2 i

1 9 111 129.45 1 3039 .823 1.064 3233 .876 4.781 26.38 2 1

1 9 112 136.05 1 3357 .813 1. 112 3735 .904 4.838 29.50 2 i

1 9 113 132.89 1 3203 .718 1.096 3513 .787 4,856 31.88 2 i

1 9 114 132.89 1 3203 .738 1.019 3264 .752 4.869 31.00 2 i

1 9 115 134.23 1 3267 .736 1.038 3393 .816 4.863 29.68 2 i

1 9 116 132.89 1 3203 .769 0.978 3131 .752 3.369 29.75 2 i

1 9 117 132.89 1 3202 .763 0.948 3036 .723 3.294 30.00 2 1

1 9 118 135. 14 1 3312 .785 1.053 3488 .827 3.363 30.12 '?

1

1 9 119 131.58 1 3140 .704 1.032 3239 .726 3.313 31.38 2 1

1 9 120 134.68 1 3289 .783 1.026 3375 .804 3.338 30.00 2 1

1 9 121 132.89 1 3203 .733 1.044 3342 .765 3.350 31.19 2 1

1 9 122 134.68 1 3289 .746 1.065 3502 .794 3.331 31.50 2 1

1 9 123 135.14 1 3312 .736 1.034 3423 .761 3.319 32. 12 2 1

1 9 124 134.23 i 3267 .747 0.994 3250 .743 3.375 31.25 2 1

i 9 125 132.45 1 3181 . 739 1. 169 3716 .863 4.B19 30.75 2 1

i 9 126 132.89 1 3203 .733 1. 186 3798 .870 4.825 31.19 2 1

* The computed energy in column 7 needs to be multipuled by a correction factor (figure 2-7) of 1.01 to take into account the location of the load cell relative to the anvil. As a result, the values of ERj. and ERj./ERy also increase accordingly.

** Denotes operator's usual number of turns used in SPT.

CME 55, 1" new rope at 468 ft/min cathead rotational speed and clockwise rotation.

A-6
Table A-5. Results for Series 10, II, 12, and 13

Fail

1 Series Blow

(ln7s)

< 2i/c height 1 Number

1 Number Number (in-lb) ERv ER^/ ERy (in-lb) ERr (ms) (in) of Turns

1 (1) (2) (3) 1 (4) (5) (6) (7) (8) (9) (10) 1 (11)

i 10 127 132.01 3160 .762 1.042 3293 .815 3.300 28.88 1

1 10 128 137.93 3450 .853 1.140 3936 .974 4.750 28.88 1

1 10 129 135.59 3334 ,770 1.125 3754 .867 4.725 30.93 1

1 10 130 137.46 3427 .809 1.092 3740 .883 3.350 30.25 1

1 10 131 136.52 3378 .810 1.092 3691 .885 3.35U 29.81 1

1 10 132 135.59 3334 .791 1.082 3609 .856 3.338 30. 12 1

i 10 133 136.05 3357 .786 0.884 2967 .695 2. 106 30.50 1

1 10 134 134.68 3289 .774 1.046 3440 .809 3.306 30.38 1

1 10 135 132.89 3203 .756 1.019 3263 .771 3.150 30.25 1

1 10 136 129.03 3019 .734 0.923 2786 .677 2.125 29.38 1

i 11 137 135.14 3312 .782 1. 134 3755 .887 4.788 30.25 2**

1 11 138 132.45 3181 .742 1.011 3217 .750 3.331 30.62 2

1 11 139 135.59 3334 .778 1.015 3388 .790 3. 156 30.62 2

1 11 140 134.23 3267 .736 0.990 323b .729 3.300 31.69 2

1 11 141 133.78 3246 .746 0.993 3028 .696 3.288 31.00 2

1 11 142 130.29 3079 .712 0.971 2988 .691 3.319 30.88 2

1 11 143 126.58 2906 .692 0.992 2883 .686 3.288 30.00 2

1 11 144 133.78 3246 .810 1.032 3348 .83b 3.331 28.62 2

1 11 145 133.78 3246 .745 1.030 3343 .767 3.331 31.12 2

1 11 146 130.29 3079 .698 0.979 3017 .634 3.313 31.50 2

1 11 147 130.72 3099 .760 0.916 2839 .696 3.288 29. 12 2

1 12 148 125.00 2854 .692 1.052 2978 .727 3.344 29.25 3

1 12 149 120.12 2617 .591 0.982 2570 .580 3.306 31.62 3

1 12 150 124.22 2799 .689 1.017 2846 . 701 3.325 29.00

1 12 151 121.95 2697 .637 0.989 2667 .630 3.306 30.25 J

1 12 152 112.68 2302 .553 0.981 2260 .545 3.344 29.75 3

1 12 153 123.08 2747 .723 1.067 2933 .772 4.800 27.12 3

1 12 154 125.79 2869 .661 0.987 2834 .653 3.331 31.00 3

1 12 155 123.08 2747 .665 0.962 2645 .640 3.313 29.50 3

1 12 156 123.46 2764 .690 1.066 2948 .736 3.363 28.62 3

1 12 157 123.46 2764 .642 1.024 2830 .657 3.3Z5 30.75 3

1 13 158 90.09 1472 .363 1.067 1571 .387 3.338 29.00 4

1 13 159 72.99 966 .246 1.244 1202 .307 4.981 28.00 4

1 13 160 84.39 1291 .357 1.115 1439 .397 3.563 25.88 4

1 13 161 83.68 1270 .317 1.105 1403 .350 3. 150 28.62 4

1 13 162 67.00 814 .207 1.103 897 .228 3. 156 28. 12 4

1 13 163 84.39 1291 .390 1.259 1626 .492 4.913 23.62 4

1 13 164 76.92 1073 .290 1.282 1375 .372 4.944 26.44 4

1 13 165 76.92 1073 .300 1.661 1782 .499 6.444 25.50 4

1 13 166 79.84 1156 .348 1. 103 1275 .383 3.050 23.75 4

1 13 167 83.86 1275 .328 1.222 1559 .401 4.908 27.75 4

* The computed energy in column 7 needs to be multipuled by a correction factor (figure 2-7) of 1.01 to take into account the location of the load cell relative to the anvil. As a result, the values of ERj. and ER^/ER^ also increase accordingly.

** Denotes operator's usual number of turns used in SPT.

CME 55, 1" new rope at 468 ft/min cathead rotational speed and clockwise rotation.

A7
Table A-6. Results for Series 14

Fall

1 Series Blow Vi < 2l/c height Number I

1 Number Number (in/s) (in-lb) ERv ERp/ERv (in-lb) ERr (ms) (in) of Turns I

1 (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) 1

1 14 168 136.52 3380 .779 1.035 3499 .806 3.331 31.00

1 14 169 137.93 3450 .815 1.027 3542 .836 3.313 30.25

1 14 170 134.68 3289 .758 1.055 3469 .799 3.313 31.00

1 14 171 134.23 3267 .778 0.993 3244 .772 3.306 30.00

1 14 172 137.46 3427 .821 1.038 3558 .852 3.338 29.81

1 14 173 135.59 3334 .756 1.003 3345 .759 3.306 31.50

1 14 174 137.93 3450 .792 1.016 3505 .804 3.294 31.13

1 14 175 134.23 3267 .710 1.008 3295 .716 3.306 32.88

1 14 176 135.59 3334 .781 0.997 3325 .779 3.319 30.5

* The computed energy in column 7 needs to be multipuled by a correction factor (figure 2-7) of 1.01 to take into account the location of the load cell relative to the anvil. As a result, the values of ER^. and ER^/ERy also increase accordingly.

** Denotes operator's usual number of turns used in SPT.

CME 55, 1" new rope at 648 ft/min cathead rotational speed and clockwise rotation.

Note that there are no data available for Series 15 and 16.

A8
Table A-7. Results for Series 17

1 Series

1 Number

Blow

Number (in/s) (in-lb) ERv (in-lb) ERr

2x./c (ms)

Fall

height

(in)

Number | of Turns I

1 (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11; 1

i 17

1 17 199 200 129.45

131.58

3039

3140

.779

.729 0.9330.940

2834

2951 .726 .686 3.5193.538

27.88

30.75

2** 1 2 1 17

1717 1 203 1 132.01 1 3160 i .740 1 0.973 3074 1 .720 3.525 1 3U.5U i z

17 1 204 1 135.59 1 3334 i .774 1 0.971 3236 1 .752 3.544 1 30.75 1 2 17 1 205 1 130.72 1 3099 1 .744 i 0.958 2969 1 .713 3.575 1 29.75 1 2 17 1 206 1 135.14 1 3312 1 .754 i 0.932 3886 1 .7U3 3.588 1 31.33 1 2 17 i 207 1 135.59 1 3334 1 .753 1 0.871 2905 1 .656 3.656 i 31.63 1 2 17 1 208 1 135.14 1 3312 i .748 i 0.943 3122 1 .705 3. 500 1 31.63 i 2 17 1 209 1 129.45 1 3039 1 .742 1 0.995 3024 1 .739 3.594 1 29.25 i 2 17 1 210 1 134.23 1 3267 1 .732 1 1.032 3371 1 .755 3.594 1 31.8a 1 2 17 1 211 1 129.87 1 3059 1 .728 i 1.024 3130 1 .745 3.588 1 3U.00 1 2 17 1 212 1 133.33 i 3224 1 .755 i 0.994 3206 1 .751 3.494 1 3U.50 1 2

17 1 213 1 134.68 i 3289 1 .755 1 0.971 3193 1 .733 3.469 1 31.13 1 2 17 1 214 1 136.52 i 3382 1 .757 1 0.934 3155 1 .707 3.669 1 31.88 1 2

17 1 215 1 128.62 i 3000 1 .742 1 1.019 3057 1 .756 3.481 1 28.88 1 2 17 1 216 1 134.68 1 3289 1 .734 1 0.985 3242 1 .724 3.738 1 32.00 i 2 17 1 217 1 128.62 1 3000 1 .720 1 1.060 3183 1 .764 3.675 1 29.75 1 2 17 1 218 1 121.21 1 2664 1 .604 1 0.817 2177 i .494 2.294 i 31.50 1 2

* The computed energy in column 7 needs to be multipuled by a correction factor (figure 2-7) of 1.01 to take into account the location of the load cell relative to the anvil. As a result, the values of ERj- and ER^/ERy also increase accordingly.

** Denotes operator's usual number of turns used in SPT.

CME 55, 1" new rope at 468 ft/min cathead rotational speed and clockwise rotation.

Note there is no Series 18.

A9
Table A-8. Results for Series 19

Fall

Series Blow V

.

(m/s)

height Numbe r Nunbe r Numbe r (in-lb) ERj-ZERy ( m-lb

)

ERr (ms) (in) of Turns

(1) (2) (3) (4

;

(5) (6) (7) (8) (9) (10) (11)

19 1 125.00 2834 . 675 0. 769 2180 .519 2. 525 30. 00 3 **

19 2 119.05 2570 . 680 0. 846 2174 . 575 2. 500 27.00 3

19 3 1 1 9 . 40 2586 . 675 0. 893 2308 . 602 2.494 27 . 38 3 19 4 121.21 2664 . 702 0. 797 2124 . 559 2. 463 27. 13 3 19 5 124. 22 2798 . 678 0. 830 2323 . 562 2. 494 29. 50 3 19 6 122.32 2714 . 665 0. 789 2141 . 525 2.4b9 29. 13 3 19 7 121.21 2664 . 680 0. 809 2157 . 550 2.463 28. 00 3

19 8 118.34 2540 . 666 0.877 2228 . 584 2. 463 27 . 25 i

19 9 123.84 2781 . 694 0.741 2350 . 586 2.469 28. 63 3 19 10 120.85 2648 . 676 0. 874 2315 . 590 2.463 28. 00 3 19 11 121.58 2681 .696 0.858 2301 .598 2.469 27.50 3

1 Q L i . JO 1 ZOO 9 A ft 1i Aft 1 • DO I n ft A n 9 9 =i 9

• Jli. 0 / ^ A / . 430 0 U IT ZO . i J J 19 13 120.12 2617 .659 0.943 2466 .621 2.463 28.38 3 19 14 121.58 2681 ,660 0.888 2380 .586 2.469 29.00 3 19 15 115.27 2410 .656 0.883 2127 .579 2.581 26.25 3 19 16 120,85 2648 .685 0.803 2128 .550 2.456 27.03 3 19 17 121.95 2697 .683 0.923 2489 .630 2.469 28.19 3 19 18 125.39 2851 .685 0.890 2537 .609 2.463 29.75 3 19 19 125.79 1 2869 .675 0.810 2325 .547 2.538 30.38 3 19 20 127.80 2962 .648 0.961 2546 .623 2.469 32.63 3 19 21 121.21 1 2664 .671 0.886 2360 .594 2.525 28.38 3 19 22 121.21 1 2664 .672 0.917 2445 .617 2.488 28.31 3 19 23 123.08 1 2747 .677 0.880 2416 .595 2.438 29.00 3

19 24 121.21 2664 .656 0.773 2U59 .507 2.456 29. OU 3 19 25 128.62 3000 .683 0.883 2648 .b03 2.500 31.38 j J

The computed energy in column 7 needs to be multipuled by a correction factor (figure 2-7) of 1.01 to take into account the location of the load cell relative to the anvil. As a result, the

values of ERj. and ERj-ZER^ also increase accordingly.

Denotes operator's usual number of turns used in SPT.

GlE 750 ATV, 1" new rope at 169 ft/min cathead rotational speed and counterclockwise rotation.

A- 10
Table A-9. Results for Series 20 and 21

Fall

Series D low V . 2)(, /c height Numbe r r^'umber Numbe r in/ s ; 1 1, ln~X d; ERf /ERy (, in Id ; ERr Cms

;

\ In; of Turns CW 1 \^

)

\^

)

f' ft c R ^ Mil (. 1 i

;

1 Z. H- ZH • D J J n RAT 9 1 A 1 z m i sft 1 J . / i 7 LI7 7 7 s * Lj

zu 2 1 "^fi OS 1 J J J / . / O D nU ftQft . D 7 D Z J J / SA7 7 1 llf^ 'ui sn TJ 19 9 "^9 1 1 Z Z • J Z j Z9 7/ 1

1 AH fl R9 'n U . o Z J

9 9 A 0 Z Zn U

'^ *^ft

. J JO 7 11'* )R 7 t^ Zo . / J J 90 A•4 1 Z. U • JO 1 Z9 QOf^ 7 UD h 7 fi

• 0/0 U. y 07 ZO7ft 7/ J h7f"l . 0 / u Ml 11

1

JU111 . h9DZ

90zu 1 9(^ Qft 1 Z9Q9A 7 ZH . D O ^ n q7 T 9ftAS ZOH _> ftftA « D D H J

T, • 7hq / O 7 J(flU ft7 . U Z, J1 ZU90 D 1 9A Qft 1 i ZD • ? 0 j Z9Q 9 A 7 Z4 • DOU fU1 A 7 T . o / J

9 S S S ^7 7 7 1 7 S J 1 . oz J ZU90 7 i

] 97Z / • J 7 1 Z9QA7*4 J . DDU U • o DU 9 S ^ 9 Z J J Z • JO / 7 1 1 1 J i . OO J ZU90 QO 119^ 7 ftO I / • o u Z 7 U Z. . D H D nU R A s . O H _J 9i JSOAV H Sift y 1 7 S JZ17 7 S . / J J1 ZU90 Q 1 9 Q Zi S ! JU"^0 J'IQ7 . Do i n 7 7 7 9 A A =^9 ^ . J^.J y 111 J

11i • MROO J ZU90 i

1 0u 1 9h ! 9Q9A ^ 7 ZH ft s s n 7QR ^9TJ J J . J ^ -> 2 119 11J 1 . RRo o 3 ZU90 \ \ 131.15 3119 .680 0. 784 2444 . 533 2.119 32.7 5 3 90Zu 1 9 1 z

19'^ 9.L J1 9nZU 1 "K J

^t?Z 9Z A*4 n R "ift ZD 7 D . JSRft o o 7 111 J17z. . RRo o J1 90ZU 1 L 197 '^Q 9Z Q7 AH J1 . O <1 ItU . RO 11 Ro 9 AOQ . J H 2 . 1 3a 31.75 3 ZU90 1 t; i J \^\ IS 3 90ZU i 0 J.19ft Z O A 9 • D Z JUU u . O H 7 flU • RO J

S Ro z.9 JS7h/ y • JSSRJO 2.131 33 00 3 ZU90 1 7 1 "^S 1 A 1 1 9 .714 0 805 2667 .57 5 2.119 33.12 3 90ZU i 0 3 ZU90 1 Q 1 "^9 RQ ! i J Z » O 7 1 3203 . 707 0. 824 2641 . 583 2.094 32. 3a 3 ZU90 90ZU 11 9Z Q7 • ASJ

"^0 "^Q JU J 7 .DUO II Ri 1 2556 . 562 2.125 32. 50 3 90zU 9 1 Z 1

1 9 Q AS 1 i Z 7 • H J j "to "^Q JU J 7 ft 7 7 n Q 7

1

9Q S9 .ftQ _>0 SR 3 7 b9 3Z. 06 3 90ZU 9 9 Z Z i

1 Z9 JS • 7/ Q7

9ft ZO hQD 7ft S . U -J D fl R 7ft 9 S 1 S7 S 2.156 31.25 3 90ZU 9Z J 1 1 IS J i11i Q7 ftQ 1 ri Rsn 2653 . 588 2.113 32.25 3 onzU 9 h Z4 1 9 A Qft i Z D • 70 9 Q 9 A Z 7 Zh ftft7 . D D / U . o D 7

9Z JS A4 1i . JSRII O VJ 7 1 7 S 3J . 31 J1 20 25 129,87 3059 .b81 0.884 2705 .603 2.113 32.0b 3 20 26 126. 18 2887 .645 0.839 2422 .541 2. 125 32.00 3 20 27 126.98 2924 .679 0.883 2584 .600 2. 131 30.75 3 20 28 129.87 3059 .683 0.799 2446 .546 2.125 32. OU 3 21 29 137.93 3450 .739 0.819 2826 .605 2.113 33.38 2 21 30 132.89 3203 .753 0.905 2898 .681 2. 106 30.38 2 21 31 135.59 3334 .741 0.822 2739 .609 2.113 32. 13 2 21 32 137.46 3427 .774 0.816 2794 .531 2.094 31.63 2 21 33 128.21 2981 .714 0.880 2b22 .628 2. 131 29.81 2 21 34 136.52 3380 .766 0.833 2818 .639 2. 150 31.50 2 21 35 131. 15 3119 .746 0.853 2659 .636 2. 138 29.88 2 21 36 133.33 3224 .722 0.792 2553 .572 2. 131 31. B8 2 21 37 134.68 3289 .752 0.790 2599 .594 2.113 31.25 2 21 38 131.58 3140 .744 0.867 2722 .645 2.125 30. 13 2 21 39 131.58 3140 .735 0.784 2462 .576 2. 106 30.50 2 21 40 134.23 3267 .756 0.840 2744 .635 2.125 30.88 2 21 41 132.45 3181 .730 0.856 2725 .625 2.125 31. 13 2

* The computed energy in column 7 needs to be multipuled by a correction factor (figure 2-7) of 1.035 and 1.0 for Series 20 and 21, respectively to taken into account the location of the load

cell relative to the anvil. As a result, the values of ER^ and ERj./ERy also increase accordingly.

** Denotes operator's usual number of turns used in SPT.

GlE 750, ATV

A-11
Table A-10. Results for Series 22, 23, and 24

Fall

1 Series Blow 2)t/c height Number |

1 Number Number (in/s) (in-lb) ERj. / ERy (in-lb) ERr (ms) (in) of Turns I

1 (1

)

(2) (3) f 1. \ (4) / C \ (5) (6) (7) (8) (9) (10) (11) 1

1 22 1 114.94 2396 .646 0.850 2037 .549 4.344 26.50 3** 1

• 0 / u • 0 JO J i • JO 'i 1 J \

1 22 3 128.62 3000 .667 0.311 2930 .651 4.519 32. 13 3 1

1 22 4 131.58 3140 .693 0.962 3019 .666 4.431 32.38 3 1

1 22 5 121.95 2697 .653 0.964 2600 .629 4.475 29.50 3 i

1 23 6 135.59 3334 .Ibl 0.935 3120 .709 4.375 31.44 2 i

1 23 7 132.01 3160 ,719 0.939 2968 .675 4.363 31.38 2 i

1 23 8 142.86 3701 .829 0.916 3389 .759 4.363 31.88 1 2 1

1 23 9 131.58 3140 .735 0.945 2967 .695 4.456 30.50 2 1

1 23 10 135.14 3312 .756 0.982 3253 .lUl 4.394 31.31 2 i

1 24 11 132.89 3203 .784 1.016 3254 .796 4.388 29.19 1 1 1

1 24 12 137.93 3450 .770 1.015 1 3506 .783 4.394 32.00 1 1

1 24 13 137.46 3227 .765 0.992 3401 .759 4.475 32.00 1 1

1 24 14 137.46 3427 . 780 0.991 3398 .773 4.381 31.38 1 1 1

1 24 15 136.99 1 3403 .794 0.996 1 3388 .790 4.3ai 30.63 1 1 i

The computed energy in column 7 needs to be multipuled by a correction factor (figure 2-7) of 1.02 to take into account the location of the load cell relative to the anvil. As a result, the values of ERj. and ERj./ERy also increase accordingly.

Denotes operator's usual number of turns used in SPT.

C1E 750 ATV, 1" new rpoe at 185 ft/min cathead rotational speed and counterclockwise rotation.

A-12
Table A-11. Results for Series 25, 26, and 27

Fall

1 Series Blow v. E* 2jo/c height Number 1

1 Number Number (in7s) (in-lb) ERv ERr/ERv (in-lb) ERr (ms) (in) of Turns 1

1 (1) (2) (3) 1 (4) (5) (6) (7) (») (9) (10) (11) 1

1 25 1 125.79 2869 .661 0.998 2865 .660 4.375 31.00 3** 1

i 25 2 128.62 3000 .694 1.013 3040 .703 4.394 30.88 3 1

i 25 3 127.80 2962 .694 0.922 2731 .639 4.531 30.50 3 i

1 25 4 127.80 2962 .699 1.017 3013 .711 4.375 30.25 3 1

1 25 5 126.18 2887 .687 0.978 2826 .673 4.563 30.00 3 1

1 26 6 130.29 3079 .7 53 1.032 3178 .778 4.500 29. 19 2 1

1 26 7 131.58 3140 .748 0.990 3109 .740 4.488 30.00 2 1

1 26 8 131.58 3140 .741 0.973 3054 .721 4.381 30.25 2 1

1 26 9 135.59 3334 .770 0.997 3326 .768 4.394 30.94 2 1

1 26 10 133.78 3246 .763 0.923 2997 .705 4.350 30.38 2 1

1 27 11 134.68 3289 .803 0.995 3273 .799 4.363 29.25

1 27 12 138.89 3498 .800 0.942 3295 .753 4.456 31.25

1 27 13 138.41 3474 .774 0.962 3345 .745 4.400 32.06

1 27 14 141.84 3649 .814 0.967 3529 .788 4.494 32.00

1 27 15 138.89 3498 .778 1.025 3584 .797 4.463 32.13

* The computed energy in column 7 needs to be multipuled by a correction factor (figure 2-7) of 1.02 to taken into account the location of the load cell relative to the anvil. As a result, the values of ER^ and ERj./ERy also increase accordingly.

** Denotes operator's usual number of turns used in SPT.

CME 750 ATV, 1" new rope at 88 ft/min cathead rotational speed and counterclockwise rotation.

A-13
Table A-12. Results for Series 28, 29, 30 and 31

Fall

1 Series Blow V . (m/s; ! ^r

9 11 / ZJt/c height Number |

1 Numbe r Number (. in-lb; ERy ERj./ERy C in-lb

)

ERr (ms) (in) of Turns I

1 K ^

}

V J ; i \-> J K f )

^ ft ^ {LU) /ui;1 1 \ 1

1

1 9fl

1

1

1z9

9J

1 "^n 9Q 1 ju / y • / jy 0u • AQQ D y y Z i J J ^ 1 7 9 A i^A Z . 4 JD 29 • 8U 0 1 z 1

1 9ft 1 '\ 1 '^ft 1 1 AO 7 70 OU A Aft . DDO zuy 90Q ^J^ 1 A 9 c.ft 1 Z . JO i 9 0 1 M zy . iu 0 1 Z 1

1 9ft J

1 9A ^;ft 1 1 JS « DO 1 J'^9ftQ Z.O -/ . 7/ A7d / 0U . AADO J Z9 I ft 9 i OZ . juy SOQ z

9 7 Q A • / y *+ jU9fl AO . DU 9 1 Z 1

1 9ft D 1 ^ 9 ftQ 1 1 J Z • O 7 1 jZU J 1 LI Z9 J9 AAHD A7 • J*4 / 9 AO A Z • dUd 90 A( I jU • ou 9 1 Z 1

I 9ft 7/1 9 ftQ 1 i J z « o y 1 1 9n ^ J ZU J . / JO 0 7 1 A zzoo 9 9ftH ^ 97 • jZ / 9 W 9ft Z. o JO 9 1 ( \l\ J i . uu 9 1 Z 1

1 9ft QO\ 'X) 1 ^ 1 l-J L m L J \ J i

1 iI Qy 7 "^9

• / jZ 0 A '^A U . 0 JH 90A 1 A 7Q . H / y

9 W 1 9 Z . o i J jU.HU 9M 0 1 Z 1

1 9 ft Q 1 1 "^ft 1 i J i JO 1 9 I An 7 9 Cl * / zy 0 7 =^ A U. / J't 9 9 A Z jD JA Q . jH-y 9 A Z • H jU 9("l in 1 JU • ou 9 1 Z 1

1 9 ft

1 Zo 1 niU 1 9 C 9 1 i JO

•

jZ 1 9 9ft n J joU 7 AQ . / oy 1 M A ^7 1 U. D^ / 9 9 1 Q ZZ i y . jUj 9 7 Z. J / J

9 1 /,f\ 0 1 Z 1

1 9 ft i i i J J • i'^ 1 9 9 19 J J i z7 A 9 . / Dj ( \ 7 fi 9 U • / U J9 9 9ft Z J Zo R 9A . J Jo 9 1 Q z . J i y9 1 fiM J A . UU 0 1 Z 1

1 9 ft

1 Zo 1 9 i z

] 9 A n '^ 1 1 JO • U J j 9 9 7 J J J / 7 A A . / DO O 7AA 1 U . / HO 9 '^OA Z jUh> . J / 19 A K Z . H JO 9 1 9n ji . jU 0 I Z 1

1 9 C 1 9 i J J J J I 9 9 9 A jZZ'^ 7 90 • / jU il 7 A K 1 9 / O A t; A A 9 /. /. A ji . OU 2 1

1 9ft

1 Zo 1 A 1 9 1 A 1 99 19 J J i Z

7 '^A

. / J^ 0 A A 9 U • 0 D J

9 I Q 1^ z i y JRO( 1 • jUU 9 7 /. A j1 • hV I 9 1 z 1

1 ZO 1 c

i J

1 9 A 0 9 1 1 JH . Z J j 9 9 A 7 jZd / 7 7 9

, / / Z U . D / D 1 9 9n w ZZUo 9 1 • JZ 1 Z. / JO 3U. 20 i 0 I z t

1 Zo 1 A I 9 Q 9 7 1 i -jy « J / 1 9 9 9 J J Z J

7 R Q 1 • / oy 1 O A /i A 1 U . OHo 9 9 7 A ZZ / D . J i U9 A 1 Q z . D 1 y

9 1 on J i . yu 1 Z 1

1 9ft 1 7 1 /1 9A QQ 1 JhU 9An 9J 7 Afl . / D U 0 Aft U. OO J j Z J J J^ 9 1 . J Z 1 9 Aft 1 Z • Do 1 jZ99 ori

. uu i 2 1

1 9 ft 1 ft io 1 9A f^ft 1 i JH , DO 1 jZo 9 9 ft 0y7 A A 1 O ft 1 9 U . O iZ 9A7 1 ZD / i K OA . DUD 9 9A 9 Z . JO J J i

.

jU 1 9 1 Z 1

1 9ft

1 Zo 1 Q 1 9Q 97 1 i J 7 • J / 1 n c 9 9 J Z J

7 ftO I ("1 70A ZHo 9Aft 11 . jnyAQ 9 AAA jZ. 99 9ZU0 1

1 Z 1

! 9 Q

i -^o 9nzu 19 7 Q 9 1 i J / . y J 1 9 A J^ jU 7 7 O i • / / U 1 ri A U A 1 u. oy D j 9ZhUZ A O 9 ^; 9A • J JD 9 Q '^n z . y jU OZ.UU 9 9 nn 1 9 1 Z 1

1 0 Q

1 9 1 Z

1

1 9 ft A 1 1 i JO »H I j 9 / 7 /. JH / 47 7 9 n 7 !-t 9 U. / OZ 1 9 7 1 A Z / J. D Am A

• DU^ 9 97 c: Z . J/ J

9 0 \ Ci 1 JZ. lU 1 9 I ^ 1

1 9ft

1 Zo zz9 9 1 9 '^i 1 A 1 i J J • i t I 9 9 19 J J i Z

1 i * / H J O A A Q 1 U • 0 D y 1 9 9 11 ZZ i 1 AQ 7 9 A 9 ^ Z . OZ J9 1 Ui 1 1 J 1 . oU 1 9 i Z 1

i 9ft

1 ^0 9"^ Z J 1 7 1 i J / • to 1 JH"^A 9Z 7/ 7QO ' . / yu 1 0 1 u • J y i ZUZH 9 ( 1 9 A . AAA HDD 9 7 9 =i Z • / Z J

9 1 nn 1 Jl • UU 9 1 z t

1 9 ft 9 A 19ft A 1 1 i JO 4 i I JH9 A 7 /. / ^ 7 AO 1 • / DU fl 7 9 ^ 1 U* / Z J 1 9 1 Q z J i y J J 1 9 *i W 1 Z • Oo 1 99 An 1 jZ.oU I 2 1

1 9 ft

1 Zo 9 ^ Z J

19 7 Q 9 1 i J / * y J 1 9 A J4 jU 7 1 • / JO 1 O 7 1 9 1 U. / i z ZH J J^ Ail

. jHU 9 U 9 1 z • y J i

t 9 ^ /

1

jZ . jU 1 0 1 Z 1

1 9ft

1 Zo ZD9f^ 1 "^A Aft 1 i JH , DO 1 JZO 7

7 A 1 1 . / o i 0u A M Q 1 . oy y 1 zzy 9 9Q 7/ . J J i 9 7 1*^ Z • / 1 J ju9n • QOyu j Z7 1

1

1 9ft 97Z /I 9ft A 1 1 i JO ^ i 1 9 A 7 /l ft 9 7 1 • o Z / 0 7nA 1 U / UD 1 9A ^ 9 Z*4 J Z^ft A • JOH 9 7 1 Q z. / i y 1 jU9ri on • UU 1 9 1 Z 1

1 9ft

1 ZO Zo9ft 1 7 Q ^ 1 i J / y J 1 j^9 A ju'^n ft 9 S . 0 J J 1 U » DO J 1 Z9 9 A 9 J D J

'^7 9 . J / Z Z9 S7 S . J / J 9Q '^o ! zy

.

ju i 7 1 Z 1

1 9ft zy9Q 1 "^Q ftA 1 i J 7 « O O 1 J J ^ / ft ( 1 1 1 * O u i 0 AQO 1 9AAft • J J J Z.J JO 1 J^1 An 1 i . DU Z9 1

1

1 9ft JU i J J • J y 1 J J J'* 7 Q A 1 • / y H j 0U A7 9 1 . 0 / Z I ZZH 9 7A 1i • J jh z9 . 7/ AQoy 1 jU90 (Ml 1 . UU j 7 I Z 1

1 9ft 1

1 9Q Of. 1 1 J 7 • O U j J'^SJ A7H / ft9 A 1 . OZO { 0 70H 1 9S1 ^ J 1 1 1 a J0*4 Z9 A 1 . D J 1 jU^n 70 1 • / U 1 Z9 11

1 9ft

1 J z9 1 "^ft A I 1 i J O • 4 i 1 JTA7H / AH 7ft 9 1 . ' o z 0U A4 7 1 . O 7 / I Z9 A4 9 1 Z. i. SA S . J't J 9z 7 SA 1 . / jd J

^1 kO 1 1 . OU 1 Z9 11

1 9ft

1 Zo 1 9 Q 97 1 1 J y • J / 1 9 =^ 9 9 J J Z J 7 7 Q 1 • / / y 1 0 A 9 9 1 U • 0 J J 1 9 9 9 1 Z Z J i AQ 9 . *4y J

9 Sk 1 Z • JO 1 jZ99 90 1 . jU 1 9 i Z 1

1 9 Q

1 z

9Zl 1 -J^ 1 117 90 1 i i / • JU 1 ZM-y 9AQ J^ i^ftO 1 . jOU 1 fi A A 1 1 U . DO i 1 i1 AD S 1 + J J. "^ft

. jO J

9 n( 1

A

J . UUD 1 JH9A xn 1 • OU 1 J 1

1 9Q J J 1 1 1 9 Aft 1 z9 ju90 Z9 '^i 1 A 1 . J i D 1 OU.J jy9Q 1

1 1

I ZHU 9AO+ 9 7 ft • Z / 0 J9 . Qy KKoo 1 9 1 QO 1 J i . yu 1 J 1

1 9 Q 1 1 Q An 1 9 "^ft A Z JO 0 S A"^ 1 • J4J 1 Ou AQ 1 . J oy 11 A7 9 + i 4 / Z . juy 90Q 9 ftk 1 1 J . 00 i jH9 A nn 1 . UU 1 9 1 J 1

1 9 Q '17 ' J / 11 1 n 1 Q 1 ZZU 9 90 9Z1 ft 1 . J 1 o 1 9 A r 1 n 1 j'+. UU 1 9 i J 1

I 9 Q 9ft JO 1 jH, 9 A n n 1 UU 1 9 1

1 30 39 142.35 1 3675 . 804 0.812 1 2983 .653 2.388 1 32. 6 1 I 1

1 30 40 ; 140.85 1 3597 .811 1 0.696 1 2506 .565 3.331 1 31.7 1 1 1

1 30 41 144.93 1 38U9 .853 0.698 1 2658 .596 2.675 31.9 1 1 1

1 30 42 1 145.45 1 3837 .863 0.647 1 2482 .558 2.594 31.8 1 1 1

1 30 43 1 144.93 i 3809 .857 1 0.688 1 2619 .589 2.881 31.8 1 1 1

1 30 44 1 142.35 1 3675 .827 1 0.745 1 2735 .615 2.544 1 31.8 1 1 1

1 31 45 1 139.86 1 3547 .821 1 0.724 1 2567 .594 2.831 1 3U.9 1 2** 1

1 31 46 1 137.46 1 3427 .765 1 0.600 1 2U55 .459 2.913 32.0 1 2 1

1 31 47 1 134.23 1 3267 .759 1 0.687 1 2244 .521 2.763 1 30.8 1 2 1

1 31 48 1 133.78 1 3246 .766 1 0.613 I 1990 .470 2.738 1 30.2 1 2 1

1 31 49 1 142.35 1 3675 .817 1 0.629 1 2311 .514 2.756 1 32.1 1 2 I

* The computed energy in column 7 needs to be multipuled by a correction factor (figure 2-7) of 1.028 to taken into account the location of the load cell relative to the anvil. As a result,

the values of ER^ and ERj./ER^ also increase accordingly.

** Denotes operator's usual number of turns used in SPT.

Load cell output weak. Data questionable.

CME 55, 3/4" old rope at 180 ft/min cathead rotational speed and clockwise rotation.

A-14
Table A-13. Results for Series 32

Fail

1 Series Blow ^i

\ in/ s ; 1 I, in i D

;

2A/c height 1 Number 1

1 Number Nuinbe r ERJ. / ERy (. i n i D

;

ERr Cms J (.in; of Turns 1

1 (, 1 ; K-i ) 7 ^

K '

)

(. 1 i > 1

1 1

0

1 i JO * H L \ T /i 7 /i . OUj n 0 7 u QA7 Z . JO 1 T f 1 u 1 2 ^ ^ 1

t T O

1 32 o 1 Z 1 32 3 132.89 1 3203 . 735 0. 364 1164 . 267 1 . 7 50 31.13 2 1

1 32 4 137.46 1 3427 .764 0.410 1405 .314 1.394 32.00 2 1

1 32 5 137.93 1 3450 .770 0.383 1321 .295 1.250 32.00 2 1

i 32 6 137.93 3450 .752 0.205 708 .155 1.744 32.75 2 1

1 32 7 141.84 3649 .784 0.364 1330 .286 1.206 33.25 2 1

1 32 8 137.93 3450 .730 0.231 .798 . 169 1.594 33.75 2 1

1 32 9 142.35 3675 .766 0.370 1358 .283 1.213 34.25 2 1

1 32 10 140.85 3597 .742 0.378 1360 .281 1.244 34.63 2 1

1 32 11 141.34 3623 .746 0.338 1225 .252 1.263 34.69 2 1

1 32 12 140.35 3572 .746 0.362 1292 .270 1.219 34. 19 2 1

1 32 13 141.34 3623 .742 0.350 1269 .260 1.231 34.88 2 1

i 32 14 139.86 3547 .729 0.257 913 . 188 1.256 34.75 2 1

1 32 15 139.86 3547 .742 0.285 1013 .212 1.694 34.13 2 1

1 32 16 142.86 3701 .769 0.394 1460 .303 1.488 34.38 2 1

1 32 17 140.85 3597 .737 0.384 1383 .283 1.531 34.88 2 1

1 32 18 140.85 3597 .747 0.268 962 .200 1.600 34.38 2 1

1 32 19 141.84 3649 .790 0.225 821 .178 1.575 33.00 2 1

1 32 20 135. 14 3312 .731 0.276 913 .201 1.619 32.38 2 1

* The computed energy in column 7 needs to be multipuled by a correction factor (figure 2-7) of 1.13 to take into account the location of the load cell relative to the anvil. As a result, the values of ERj. and ERj./ERy also increase accordingly.

** Denotes operator's usual number of turns used in SPT.

CME 45, old rope at 60 ft/min cathead rotational speed and clockwise rotation.

A- 15
Table A-IA. Results for Series 33, 34, and 35

Fall Series B low V

.

fin)'?')

F E* / c he i t N utnbe r

Ml 1 mKo 1" IN UlliUc L MiLII mUl V\ci TL ( in-lb

)

ER ER /ER ( in~lb

)

FRn (ins )f 1 n 1 of Turns

( 1

~) (2) (3) (4) (5) (6) (7) ( 10') MM\ I

33 I 125. 79 2869 .638 0. 505 1449 . 322 3.37 5 32. 13 2**

33 2 136.05 3357 .741 0.498 1670 .368 2.894 32.38 2 33 3 133.78 3246 .720 0.631 2047 .454 2.656 32.19 2 33 4 144.40 3782 .809 0.503 1901 .407 2.619 33.38 2 33 5 144.93 3809 .809 0.502 1912 .406 3.063 33.63 2 33 6 144.40 3782 .800 0.509 1 1924 .407 2. 194 33.75 2 33 7 136.99 3403 .739 0.582 1982 .430 2.075 32.88 2 34 8 132.89 3203 .647 0.547 j 1751 .354 2.631 35.38 3 34 9 1 131.51 3140 .641 0.455 1428 .291 2.881 35.00 3 34 10 126.18 2887 .682 0.546 1 1577 .372 3.894 30.25 3 34 11 1 131.15 1 3119 .713 0.526 1 1641 .375 3.131 31.25 3 35 12 1 140.85 1 3597 .767 0.533 1 1919 .409 2.894 33.50

35 13 j 146.52 3893 .796 0.464 1 1808 .370 3.506 34.94

35 14 1 146.52 3893 .792 0.468 1822 .371 2. 175 35.13

35 15 144.40 1 3782 .812 0.462 1748 .376 2.125 33.25 1 35 16 145.45 1 3837 .784 0.490 1 1880 .384 3.325 34.94 1

The computed energy in column 7 needs to be multipuled by a correction factor (figure 2-7) of 1.05 to take into account the location of the load cell relative to the anvil. As a result, the values of ER^ and ER^/ER^ also increase accordingly.

Denotes operator's usual number of turns used in SPT.

GIE 45, old rope at 60 ft/min cathead rotational speed and clockwise rotation.

*U.S. GOVERKMENT PRINTING OFFICE : 1981 0-353-615 A-16
NBS-n4A (REV. 2-BC) U.S. DEPT. OF COMM. 1. PUBLICATION OR 2. Performing Organ. Report No. 3. Publication Date BIBLIOGRAPHIC DATA

REPORT NO. August 1981 SHEET (See instructions) NBS BSS 135

4. TITLE AND SUBTITLE

Energy Measurement in the Standard Penetration Test

5. AUTHOR(S)

William D. Kovacs , Lawrence A. Salomone, and Felix Y. Yokel

6. PERFORMING ORGANIZATION (If joint or other than NBS, see instructions) 7. Contract/Grant No. NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE 8. Type of Report & Period Covered WASHINGTON, D.C. 20234 Final

9. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City. State. ZIP)

Same as above.

10. SUPPLEMENTARY NOTES

Library of Congress Catalog Card Number: 81-600101

I I Document describes a computer program; SF-I8S, FlPS Softv^are Summary, is attached.

11. ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here)

Geotechnical engineers in the United States commonly use the Standard Penetration

Test, SPT, in subsurface investigation for routine foundation designs. It has

been said that perhaps up to 80 to 90 percent of the routine foundation designs

are accomplished by the use of the SPT "N" value. Despite efforts to standardize

more details of the SPT procedure, variability between tests is inherent under

present guidelines.

A field measurement system and procedure which measures the energy delivered

by a drill rig system were developed and successfully used to study the factors which

affect delivered energy. Results are presented which indicate the energy delivered

by certain drill rig systems used in engineering practice. Also, the transmission

characteristics of certain hammer /anvil systems are examined. Guidance on the need

to measure the actual fall height of the hammer during the Standard Penetration Test

is provided based on the findings of the study.

12. KEY WORDS (S/x to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolons)

energy measurement; field instrument force measurement; field testing; in-sitii

testing; soil mechanics; transducers

13. AVAILABILITY

Qx] Unlimited

I I For Official Distribution. Do Not Release to NTIS

f"xl Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402.

[331 Order From National Technical Information Service (NTIS), Springfield, VA. 22161

14. NO. OF

PRINTED PAGES

99

15. Price

$4 .50

USCOmM-DC 6043-P80

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environmental functions and the durability and safety characteristics of building elements and systems.

Technical Notes—Studies or reports which are complete in themselves but restrictive in their treatment of a subject. Analogous to monographs but not so comprehensive in scope or definitive in treatment of the subject area. Often serve as a vehicle for final reports of work performed at NBS under the sponsorship of other government agencies.

Voluntary Product Standards—Developed under procedures

published by the Department of Commerce in Part 10, Title 15, of

the Code of Federal Regulations. The standards establish nationally recognized requirements for products, and provide all concerned interests with a basis for common understanding of the

characteristics of the products. NBS administers this program as a supplement to the activities of the private sector standardizing

organizations. Consumer Information Series—Practical information, based on NBS research and experience, covering areas of interest to the con- sumer. Easily understandable language and illustrations provide

useful background knowledge for shopping in today's technological marketplace. Order the above NBS publications from: Superintendent of Documents, Government Printing Office, Washington, DC 20402. Order the following NBS publications—FIPS and NBSIR's—from

the National Technical Information Services, Springfield, VA 22161.

Federal Information Processing Standards Publications (FIPS

PUB)—Publications in this series collectively constitute the Federal Information Processing Standards Register. The Register

serves as the official source of information in the Federal Govern- ment regarding standards issued by NBS pursuant to the Federal Property and Administrative Services Act of 1949 as amended,

Public Law 89-306 (79 Stat. 1127), and as implemented by Executive Order 11717(38 FR 12315, dated May 1 1, 1973) and Part 6 of Title 15 CFR (Code of Federal Regulations).

NBS Interagency Reports (NBSIR)—A special series of interim or

final reports on work performed by NBS for outside sponsors

(both government and non-government). In general, initial dis- tribution is handled by the sponsor; public distribution is by the National Technical Information Services, Springfield, VA 22161,

in paper copy or microfiche form.
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